Ladies and Gentlemen, imagine you're out for a stroll in your usual linear path through the countryside. You're on your way to the Goomba's house to say good morning. The sun is shinning while Mr. Koopa is out playing with his kids. Suddenly a dark shadow envelopes you from above. Some jabroni crawls out of the sewer...gross...and stomps on your head. You are taken aback...shocked...incensed even. You collect yourself, and make your way over to this over-alled oaf and prepare to give him a piece of your mind when he picks you up...humiliates you and tosses you through the air toward a stack of bricks. What nerve!? What gall!? If you had a mouth you would be speechless at this disrespect. Now, you're feeling the anger swell as you can feel your body flash red. You feel like you're going to explode!

This is the plight of Mr. Robert Omb. This is why I decided to create a monument to him, so that all of posterity could know of his struggles.

Supplies

16" Atlas Stone mold - qty. 1
Pre-mixed concrete - 180 lbs.
Gravel
Mortar (White) 40 lbs.
Concrete colorant
Clothing Dye
Concrete sealer
36" long 1" diameter wood dowel
Screw + Washer
Duct Tape
Masking Tape
Silicon
Hot Glue
Cling Warp
1/8" self adhesive foam sheet
6" PVC end cap
Aluminum bar
Aluminum flat stock
Spray paint
Trash Bags
5 gallon bucket - qty. 2
2 quart tubs - qty. 2
2' x 3/4" steel pipe
1" steel pipe floor flange
1" x 3/4" pipe reducer/coupler
2" x 1/4" bolts
Steel flat stock
2x4

Tools:

Drill + small bit
Masonry drill bit
Hammer
Chisel
Shovel
Safety Glasses
Dust Mask
Nytril Gloves
Hot Glue gun
Angle grinder w/ cutoff disc
Files
Bench Grinder
Bandsaw (not 100% necessary)

Step 1: The Vision / the Plan

I've been wanting to do this project for several years now and have been thinking about the best way to go about it. At first I considered using a steel sphere like a scavenged nautical buoy or cutting the end caps off of a cylindrical propane tank but those options proved to be either too expensive in the case of the propane tank, or too difficult to locate in the case of the buoy - i live in the middle of the desert. So I settled on a concrete statue. But then how to make the perfect sphere? I considered making my own mold out of plaster and maybe a yoga ball which I've seen other people do, but those molds tended to be a one-off and I knew I wanted to be able to make more than one concrete sphere if I liked the way it came out. Then I found a site that supplies pre-made molds for Atlas Stones. Atlas Stones are those big concrete balls used in strong man competitions. A company called Slater Hardware makes various sizes and styles of molds that are relatively inexpensive and reusable, so I asked for a 16" mold as a Christmas present from my wife last year. Let the fun begin!

The vision is to have a concrete Bob-omb statue that has a small water spout as a fuse. Ultimately this is going to be part of a larger water feature in my back yard which I am currently remodeling. In my mind I am seeing the statue lit low from the front in white, while the water spout is lit from a red light concealed behind the statue.

The plan is to use the stone mold for the body with a foam core to reduce the weight. There will be a wood dowel in the center that will be removed once the body cures. This will leave a space for the internal plumbing. The fuse cap will be formed on top of the body from blue tinted concrete. The feet will be formed from yellow tinted concrete.

Step 2: Constructing the Main Body Mold: PART 1

The Atlas Stone mold is a 16" diameter. When I received it from the supplier it had vinyl lettering on the inside that would imprint "Slater" and "16"" on any stones that were molded from it. This was easily removable by peeling it off. The mold comes in two parts and the Slater Hardware people have several really nice videos showing how to assemble the mold and create the stones. They also have advice on how to change the weights of the stones by adding foam inserts. For this attempt I was going to change it up a little and use a dowel to create a void for plumbing while also using the foam for reducing the weight. I used a 10" foam ball from a craft store. I poked a hole through the ball and stuck the dowel through so that it stuck out 3" passed the bottom. This would create a uniform 3" wall of concrete. I hot glued the foam ball to the dowel and then wrapped the whole center assembly in cling wrap. The idea behind the hot glue and the cling wrap is that I need some way to hold the foam in place to keep it from floating to the top of the concrete as I poured it, BUT... I also wanted to be able to break the dowel free easily and remove it from the center. The cling wrap would hopefully keep the concrete from binding to the wood.

Step 3: Constructing the Main Body Mold: PART 2

A small hole was drilled in the bottom half of the mold and I used a single screw and washer to secure the wood dowel in the center. When I put the top of the mold on I confirmed the 3" clearance. Just like the manufacturer used vinyl lettering to imprint their name and the size I wanted to make imprints of the eyes. I wanted them to be a little deeper so I used 1/8" foam sheets. I've done this before in concrete molding so I know it works well. I placed the cut out eyes on the outside to make sure I was happy with the placement, then used the sunlight to show me where to place the eyes on this inside of the mold. Once I was happy with the eye placement I sprayed some mold release agent that I had from previous projects all over the inside. The mold release will help extend the life of the mold. You can make your own with household items if you don't have the store bought kind. Last I taped the heck out of it per the manufacturer's recommendation.

Step 4: The Pour

The mold was placed on a bucket lined with a trash bag on top of other trash bags to help protect the ground. As you can see in the picture the body is made of plain Quikrete mix with Quikrete brand concrete colorant. It ended up taking approximately 1 3/4 bags of concrete mix and 2 1/2 bottles of colorant. The pour was done by mixing 6 quarts at a time in a larger bucket with approximately 3/4 cup of colorant each time. I had to repeat this mixture 6 times to fill the mold completely. I made each mixture slightly more runny than you normally would with concrete mix. I did this to try and make it easier to get all of the air out. After each pour I tapped on the mold for several minutes to work the air bubbles out. After the last pour I vigorously tapped on the mold for at least 10 minutes to make sure I got all of the bubbles out. Once the concrete reached the top there was a lot of excess water on the surface. This was no good because it would leave a void once it evaporated. I mixed a small 2 quart batch and added it to the top a little at a time to displace most of the water so I would have actual concrete all the way up. Lastly I cleaned the outside of the mold as well as I could. This is to help extend the life of the mold.

I left the concrete to cure for 5 days. After the first day I noticed that the concrete was already separating from the top hemisphere. I believe this happens for a few reasons. One, as the foam compresses under the weight there is a slightly smaller volume. Two, some of the water was being squeezed out of the seams of the mold also reducing the volume. Three, as the excess water evaporated the volume was reduced. The last two things made me realize that I made the mix a little too watery. The small void on top wasn't a huge deal though because it actually provided a reliable way for me to keep the outside of the concrete damp as it cured by pouring water in the top hole every few hours.

*side note- If you watch the Slater hardware videos you'll see that the guy demonstrates how he "trowels" the inside of the mold by picking the whole thing up and quickly rotating it. Yeah, that ain't happening. I'm not the kind of guy who actually uses Atlas Stones...I'm the type of guy that uses Atlas Stones to make a Bob-omb statue. A 16" stone would be 175 lbs. With the 10" foam core the weight would be about 130 lbs given that a 10" round stone is 45 lbs. With the weight from the wood dowel also subtracted from the total I estimate the final weight at around 120 lbs. Perfectly liftable, but not lift and twistable like the guy in the Slater videos. I don't want to be calling my boss to tell her I can't come in to work because I threw out my back making a statue based on a side character in a video game.

Step 5: Removing the Mold

After the allotted curing time had passed I removed all of the tape and began removing the top hemisphere slowly. Next I gently rotated the stone and knocked off the bottom half. I set it back upright and gently twisted the stick which surprisingly twisted free without any issues. It pulled right out. I had to pull out a little bit of the cling wrap that was stuck on the foam insert. The thing looks like a canon ball with eyes! I was very happy with the way it turned out.

Step 6: Fixing the Rough Spots

There were just a few rough spots that I wanted to smooth out for a better look. I bought a concrete abrasive stone thingy to do this. Its basically a sanding block for concrete and knocks all the rough peaks off. As you can see the color of the concrete lightened up significantly after fully curing but I'll take care of this later.

Step 7: Creating the Fuse Cap

For the fuse cap I bought a 6" diameter pvc cap and cut the end off to give me a 6" round form to use. The goal here was to use the top of the sphere as the bottom of the fuse cap mold. This would ensure a good fit since the cap bottom would be the exact shape of the sphere and not leave any gaps when I assembled it all. I covered the sphere with plastic wrap, set the pvc mold on top and used silicone to seal round the bottom of the mold. I also re-inserted the wood dowel to keep the space for the water spout. In an attempt to try and keep the color vibrant I tried using white mortar mix instead of regular cement. I am using RIT clothing dye which I've never used to color concrete so it may fade in the sun. This is actually the second attempt at this. (Post build note: I've only recently discovered a good powder pigment for concrete in a variety of colors that I did not try while making this project. I will try it on the next one) For the first try i only used mortar mix with no aggregate so the result was smooth and colorful but very brittle. For this attempt I added some medium sand for an aggregate to make a more firm concrete shape. The color washed out a little but it still looks good. As it cured the color faded like the main body but not too bad. I tried sanding the top afterwards to make it smoother but it just made it worse so I'm going to just be happy with the result being a little rough.

Step 8: Enhance!

To address the color fading I used a concrete sealer which also enhances the color. It didn't bring the concrete back to the very dark black from when I first took it out of the mold, but it did improve it tremendously. Before applying the sealer I also added white acrylic paint to the eye indentations.

Step 9: Playing Footsies

I racked my brain for weeks about how I was going to create the feet. I thought about sculpting them out of clay, or wax to make a mold but I'm not a very good sculptor so that probably wouldn't have looked right. I actually just wandered around an arts and crafts store for about 30 minutes looking at different products to imagine if any of them would look ok and I came to the foam aisle. I found a cone and a ball that looked like they would fit together to make a convincing shoe/foot shape for the statue. I cut the ball into quarters and the cone down the middle length-ways. The back of the cone got shaved down with a wood rasp and I joined the two pieces together with masking tape. Next I covered the whole foot with masking tape so I could use it as a blank to create a silicone mold. I built a box mold and using an oomoo 25 two part silicone kit made a mold for a foot. I made two blanks in case I messed one up, but I only made one mold. For the concrete I used the same mortar mix with medium sand and RIT clothing dye. This time the dye color was really strong. After making both feet I used a sanding sponge to smooth out the little wrinkles from the tape covering the foam when I made the mold.

A quick note about the colors. I had given a little thought to just making the whole thing plain gray concrete colored like a classic statue. Part of me worried that the colors would be so far off from what they "should" be that I didn't think it would be worth it to even try. But I really wanted the body to be black so the fuses cap and feet HAD to be colored. There are many variations of the Bobomb's coloring even in the games themselves, so I settled on the picture above with a light blue cap, orangish feet, and a metallic brass key.

Step 10: Plumbing and Dry Fitting

The plumbing is really two parts with two functions. The first part is structural. I used 3/4" gas pipe with a 1" T fitting and a floor flange. The floor flange will provide a base to help the statue stand (more on that to come). The T fitting and gas pipe will provide a conduit to pass the actual water line through. The T fitting also provides a ledge for the sphere to rest on. Once I got all the plumbing situated I assembled all the concrete pieces to see how they all looked together. I think the first sight of it all together made this grown man go "squeeeee!" with delight. I also applied some more sealer to the feet and fuse cap to help the color.

Step 11: The Wind Up Key

If the problem of how to make the feet took me weeks to figure out the wind up key took at least twice as long. I considered concrete, but decided it would be too brittle because of how thin it was. I considered plastic but figured it would warp in the sun. I considered wood but figured it would weather poorly in the heat. It had to be metal, but it had to be lightweight. Steel would be too heavy so I settled on aluminum. I purchased a 12"x6"x3/4" and a 12"x2" aluminum rod. I drew out the basic shape on the aluminum and got to work on cutting it out. I didn't have the proper tools for cutting the aluminum when I started so I began by drilling small holes around the outline to get the rough shape. Then I used files and a bench grinder to help smooth it all out. Finally I was able to purchase a proper band saw and finished refining the handle. I chiseled out a hole in the back of the body to insert the key. This actually wasn't as difficult as it sounds. I drew the circle I wanted to chisel out and made a dozen or so small bore holes using a power drill and a 1/4" masonry bit. I went around the inside of the outline like I did with the aluminum. After I got a big enough hole created I used an improvised chisel made from an old railroad spike and refined the hole. Lastly I used a sledgehammer to pound the aluminum rod through the opening to smooth out the walls.

To attach the key handle to the rod I cut a groove in the end of the rod that would fit the handle. Its a bout 2" deep. The handle fits snug in the groove but still needed something to hold it in place. I used a JB Weld product called steelstik which is a two part putty that hardens fast and is very strong. I applied the putty in the desired shape around the joint and waited for it to harden. After curing I used some different files to clean up the shape and make it look almost welded together. Next I cut down the rod length to the appropriate size for the sculpture and cleaned up all the surfaces with a wire wheel. Finally I primed the whole thing and painted it with a metallic gold paint.

Step 12: Concrete Base

You may have noticed along the way that my statue doesn't have any legs. Its a fair criticism to point this out. The issue of the legs was one of the first mental blocks I came to during the conceptual phase of this project. If I had made it of steel from a propane tank or a buoy I could have just easily welded some legs on to support it. If it was all fiberglass i would have been able to use some other lightweight material for legs and wrap them in fiberglass. Even after I settled on concrete I mulled using steel cradle on the underside of the body with steel legs. I also considered drilling two holes in the bottom and inserting two steel or aluminum rods for support that the feet would be build around. Of all the solutions I came up with the single steel pipe in the middle seemed first, the easiest, and second, it solved the support issue as well as the plumbing issue in one shot. So I took some artistic license and gave the Bobomb the suggestion of legs.

But the next problem was holding it all up with just one support, so it needed a solid concrete base. Basically its the same arrangement as a homemade tether ball pole...except without the tire. I got some 1/2" x 1/8" steel flat stock and cut it into four 6" pieces. Next I drilled holes to correspond to the floor flange and bolted the pieces onto the flange in a tic-tac-toe pattern. There are a few nuts on the underside which hold the assemble up about 1". This will allow the concrete to get under it instead of the flange resting on the wood form which could lead to the assemble busting out the bottom of the concrete once I put the weight on it. I built a simple form from a 2x4. Its just slightly wider than the body to help keep the center of gravity low and in the middle incase my dog or kids nudged it. I chose the octagon shape because it's going to be sitting on a pond liner and I thought the 90 angles of a square might pose more of a puncture risk to the liner. For this I used basic quikrete premixed concrete with no color. After I poured the concrete I did trowel the top a little to help make it a little smoother but its still a little rough. I just wanted to make sure the feet would sit flat. The base is about 3" thick fully encasing the steel and floor flange on all sides.

All in all I think it looks pretty good as a statue pedestal.

Step 13: The Installation

As you can see from the first picture the statue is being placed next to a newly installed stream in my yard. The area where the pedestal sits is a little jut-out I made just for this. The pond liner extends underneath with a sunken area so the water from the fountain will be directed back into the stream. The yard renovation is taking place at the same time as the fountain build so its still a little messy. I first set the pedestal in the correct place and checked that it was level...which it wasn't so I had to remove all of the rocks and level the ground underneath the liner a little bit. When I putt the pedestal back down i was careful to make sure there were no pebbles underneath that might puncture the liner and cause a leak in my stream. The level was still off by about a 1/4 bubble so rather than pull the liner up again I shimmed the pedestal with a rolled up piece of extra liner.

I was going to build a sling to lift the body up and on to the pipe support so that my wife and kids could help since it is fairly heavy. Ultimately my impatience won out and I just decided to He-Man the thing up there myself. Remember at the beginning when I said I'm not the type of person who actually uses Atlas stones? Yeah, I'm still not and my back reminded me of that later that evening. But we all suffer for our art I guess.

I angled the statue slightly sideways away from the waterfall in the background so you can see the wind-up key from my back porch. I think it looks rather majestic looking off into the distance wistfully.

Step 14: The Plumbing

The plumbing was fairly simple because I used the same pump as I was using for my waterfall. When I was running the 1 1/2" pvc line for the waterfall I had installed a T fitting and capped it for this specific reason. I can adjust the flow to the statue or isolate it if I need to fix or change anything. If I were going to do this in just a standing pool of water a simple submersible pump would have worked just as well. If I could go back in time I would have used galvanized pipe in the body instead of steel gas pipe. If I had used galvanized I could have just connected a pvc pipe to the bottom of the support pipe and run the water through it, but since this is plain steel pipe it would have started to rust and discolor the concrete or harm any fish I plan on putting in the pond. So instead I got some clear vinyl tubing to feed through the gas pipe. To make the spout I got a 1" pvc coupler which slides directly over the 3/4" gas pipe. I just had to file down the little lip in the middle that is supposed to stop you from inserting a pvc pipe more than half way. The coupler acts as a sleeve for a 1/2" thread-insert fitting. The insert end of this fitting is facing "down" into the sleeve while the threaded side faces "up". The insert end will receive the tubing inside the gas pipe. The threaded end allowed me to create a custom nozzle for the fountain. I took a 1/2" pvc threaded endcap and drilled a few holes to allow for a sprinkler type effect. It worked pretty well but I decided I liked the look of the unrestricted flow better so I removed the endcap and just left the open assembly for the water to bubble up through.

Step 15: Final Touches

I didn't include the lighting in this instructable because i'm not sure how permanent its is going to be. The lighting in the photo and video are simple solar powered landscape lights. They're water-proof so they can be close to the fountain. I have two positioned in front concealed by some rocks and one in the rear close behind the statue so it isn't visible from the front normally. I bought some transparent red plastic and created a lens cover to change the rear light from white to red to give the fuse effect.

This project ran for more than 2 years due to work commitments and hold ups from the larger yard remodel. I'm super excited about how it turned out though.