With a special jig, a good bit of time and a LOT of cardboard you can make the very comfortable, very groovy ball chair. Since the bulk of the material is scrap cardboard this also makes a nice recycling project.

You can upholster the final chair like I did or just paint it and fill it with pillows. The plans for this instructable are for a 4' diameter chair that will (just barely) fit through a 30" doorway. You could scale it up or down easily depending on the size of person it's for and how much "surround" you want.

The chair stands on the base by gravity alone and the unattached design allows for easy readjustment of the ball. I like sitting in it more upright, and my daughter likes it kicked farther back.

I made this for my daughter's 13th birthday and it was a big hit. She's an avid reader and it makes a perfect cozy zone to open a book in. When she saw it she called me a "mad genius" which is high praise from a 13 year old. One of her first questions was "how will I get it to college?" I think she likes it and plans to have it around for a long time. It was a big project, but well worth the effort.

Step 1: Sphere Cutting Jig

The most important part of this project is the jig. This large but relatively simple jig makes a perfectly shaped, hollow, half-sphere . The horizontal turntable and outer cutting arm cut the outside. The inner cutting arm cuts the inside surface, the hollow area of the sphere. Be aware that this jig needs to sit on a sturdy table or sawhorses. The pieces it makes are heavy so pick a place for it carefully.

The turntable doesn't need to be perfectly circular since it's the rotation, not the shape, that cuts the circle. In fact, an octagon shape would be preferable to a circle as the corners on the octagon would make for easier turning during a cut. An octagon shape would also be easier to layout and cut.

I used a few pieces of leftover 3/4 inch melamine for the turntable and base and standard 2 x 4 lumber for the swing arm and mounts. Some 3/4 inch plywood would work fine for the turntable and base. Don't use 1/2 inch or thinner material due to the weight it'll need to support. To make a round turntable use a router mounted on a long strip of material such as fiber board, screwed loosely to the radius point. Measure carefully for the center, mount the radius board and cut a perfect circle.

The swing arm arrangement is connected to its mounting points with 1/2 inch lag screws. These fasteners can be loosened to allow the arm to swing freely, or tightened to hold it in place.

Both cutters are simple utility knife blades. I used blades with holes so they could be mounted to their bases with small screws. These blades are inexpensive and easily replaced as they dull.

The inner cutter arm is made with a 2 inch by 3/4 inch piece of wood with a slot cut in one end for the swivel. Use an extra piece of stock on the other end, held in place with 2 screws. The inner cutter blade is trapped between the two pieces of wood and clamped in place by tightening the screws. The distance from the swivel mount hole to the blade clamp  will determine the inner radius of the sphere. To get a 4 inch thick wall use a 24 inch outer radius and a 20 inch inner.

I am 6' tall and this inner diameter is comfortable enough when sitting in the chair with a papasan cushion. I would've preferred to make the ball slightly larger, but getting the finished chair through doorways was the limiting factor. A larger radius is more comfortable. It's less likely to feel like your head is being tipped forward.

A point I can't stress enough is take careful measurements. Measure your doorways very carefully or you will make a cool chair that will live forever in your shop.

See the instructions on step 8 for additional tips and considerations on how big the chair could/should be.

The swivel mount for the inner cutting arm is made with a 3/8 or 1/2 inch thumb screw with a 1/4 inch hole drilled in the center of the flat portion. The swivel mounts to the turntable using nylon-insert nuts and washers. These nuts allow for a precise adjustment without slipping. The swivel must spin freely, but not wobble. Use a thumb screw long enough to go through a pivot hole in the base. In this way the swivel mount also functions as the turntable axle.

The width of the base doesn't need to be exactly as noted in the plans (72") but beware that having too small a gap between the edge of the turntable and horizontal mounts will make for frustrating cutting before the layers of cardboard get higher than the mounts. Too close and your glued cardboard will keep bumping into the mounts and have to be cut away to spin the turntable.

<p>I made one out of timber(ply) a few years back.Three inches thick. Ridiculously heavy. Aced the exam with it. Any idea of how i should go about selling it. Its never been used.</p>
Wow, that's awesome. From what I know you are the only other person to have made a chair like this. Three inches? Holy smoke, I can imagine how heavy that is. You probably could have done fine with 2&quot;, or even 1 1/2. That looks nice, what a nice effect. Did you make the base too?<br><br>Selling, I've wondered about that too. Yours looks so nice, you could certainly try on CraigsList, but you'll probably just get hounded by cheapskates. What city do you live in? There are probably design firms there or nearby, you probably need to make contacts in that realm.<br><br>My chair is just cardboard, and the upholstery is showing its age in spots. I may just donate it to my son's school, it's most comfortable for kids.<br><br>I'd love to see some other pictures of it. What school was this for?
Yes three inches was overkill.<br>I had to make the base myself i dont know of anyone with the patients who could understand it and make it and get it right.<br><br>Craigslist.. i must try that. i was thinking of ebay myself.<br>Im in europe so it could change the game plan.<br>But it only takes one buyer<br>It was for our equivalent of final year highschool.<br>Ive no pics of it finished on the inside. Similar to yours covered with red foam cushions.
<p>I made a few modifications, my inner cutter was long enough I made it into the outer cutter too, since it was easier to work with. I also used the bearings and race from a semi truck instead of what gdufford used. the outer arm will still come in handy for making the stand; however.</p>
My plan is to build a fabric/vinyl inflatable like chair, then pump it full of expandable foam, somewhat like &quot;La Mama&quot; by some furniture designer who's name i momentarily forget. Worked with cardboard all last semester in slotted and stack designs. I know the toil involved haha
<p>If I were you I would make a negative mold for your chair. You could design it in 3d, then &quot;slice&quot; it like they do for 3d-printed models. Cut each slice out of cardboard then assemble it in layers. That might be too large a cavity to fill with just foam and have it set properly, but at least that way you could control the shape precisely. </p><p>Maybe in addition to the negative mold you could also have an insert piece, a matching positive that is something like 10&quot; smaller all around. Hang/position that in the center of the mold and fill the void with your foam. The positive portion will remain in the chair. It would give the final chair needed support. Does this make sense?</p><p>I recently made a Lovesac-style bag chair. The size is 4' x 4', 30 inches tall. It's just a big brick shape filled with shredded foam. It's SUPER comfortable, but it would be nice if it had a little support in key areas. It flattens out pretty quickly and needs to be re-plumped often. If I make another I might put some inflatable innertube inserts to keep certain areas (like the back) stiffer than others.</p>
Any suggestions on how to make a light weight thin half-sphere 3X the size of this one?
Jeez, 3 times the size is massive. In theory you could just scale up the jig, but at 12 diameter and 6' height it could be challenging to move. I would still suggest cardboard, the 3.5 inch wall of my chair is so strong I might make another chair thinner, like 2.5 inches thick. It would be roomier and still plenty strong. <br> <br>If you made a big sphere, 12 x 6, how would you move it? Or maybe you wouldn't need to. <br> <br>Good luck!
When I said it would be a challenge to move, I meant the jig. Someone started a chair like this before and motorized the jig. I don't think they finished though. The motor setup was tricky and not real reliable.
Impressive, great dedication. Looking for a less strenuous plan, but I'd make this when I have more time (sadly, school project deadlines don't allow for much material processing). Thanks for posting
Man this is clever! Lets see if I can replicate the result! Fingers crossed...
you should sell it for like 300 how dose it hold up ?
lol 300... it's not some cheap factory made piece from China. Cardboard is incredibly sturdy when glued and shaped like this. <br> <br>This chair takes countless hours and is handmade by an artisan... it's worth thousands.
wow thanks could i add fiberglass resin to the end project for extra strength if needed
i need alot of cardboard. and alot of time to get it. DAMN YOU AUSTRALIAN COCKROACHES BREEDING IN CARDBOARD
Whoa, impressive! How long did this take for you to finish? If someone made these, I would definitely buy one. It seems impossible to make one, yet here I stare at the finished product.
With bits of time here and there, maybe 10 to 12 hours a week on average, this took awhile. Got the idea mid-summer, got it mostly finished by October 31st (daughter's birthday) and completed the inside upholstery by Thanksgiving. <br><br>Thanks for the offer to buy, but to make a &quot;living&quot; building these I'd have to charge $5,000, you know? Definitely a labor of love. I joke with people I know that my favorite projects are big, novel, and more than a little impractical.<br><br>Thanks again!
I feel certain you could fetch 5,000 for this chair especial if it were marketed as art .Very impressive !
What an impressive project! And your instructable is equally as impressive!<br><br>It's wonderful all the consideration you put into the practicality of each element (like the design of your jigs, ergonomic considerations for the base height, and the ability to get it through doorways). I love that you continued to think about how to improve the project both during its construction and well after it was done.<br><br>I love the idea of making it with carpet pads. Do you think it would have to be thicker than 4&quot; to reasonably keep its shape? You've inspired me and I would really like to try it when I am able (though it may be a few years until I get a suitable workspace - long term goal). I'll certainly let you know how it goes if I am able to do so.<br><br>You're a dedicated maker with serious brains, talent, and consideration for your daughter and your project.
I generally like to plan out my projects to a high-degree (drives my wife crazy at times), but I'm also not against winging-it on smaller stuff. That being said, this build was just way too big and risky to not plan carefully. <br><br>If it would've been even 1/2&quot; too big to get through a doorway, it would've been crushing. It's a weird shape and hard to simulate moving it. I literally had about 1/4&quot; to 3/8&quot; leeway getting into my daughter's room. That was a big &quot;whew!&quot; moment.<br><br>The carpet pad version would be interesting. It could be bigger, and the squishyness would help getting it into rooms. These chairs are heavy though, a squishy material would sag and/or deform. It could get all pancakey just sitting there. <br><br>I don't think it would need to be thicker at the current size, maybe not even if bigger. Carpet pad is pretty dense. The 4&quot; (cardboard) wall is VERY solid. If I could turn these around quicker (and didn't have a regular job, wife, kids, etc.) it would be interesting to know how thin the wall could be. <br><br>Thanks for the compliments, they only make me want to keep going!
That's an amazing project, I think it would have taken me like six months, if I even had the patience to finish that is. The design for the machine is impressive enough, but the scope and detail involved, wow.
Hey gdufford, I'm sure you're married, but... will you marry me? I so long for a creative man in my life, to share my &quot;honeydo&quot; list with. I could keep him busy for YEARS! (Sigh) <br> Also so good to get praise from a teenager, especially your own!<br>You're the man!
GREAT JOB!!!! I wonder if you could build a jig that could hold a router and do the same thing with wood?
Thanks! Actually, I used a router for the jig that cut the concave part of the base that the chair sits in. Some of the cuts were just too shallow to do with a blade.<br><br>I'm also making another chair with the same jig. I bought a rotozip that I'm going to mount on the jig. The rotozip should be the right combo of power and weight. Not too much, not too little. Hopefully I'll get smoother cuts and the chair will look better unupholstered if I decide to leave it &quot;natural&quot;.<br><br>Yeah, you could totally use wood planks. Shipping palette wood would work well, but I have a buddy that used palette wood for fence pickets and he said it was a lot of work pulling them apart, removing the nails and bits, all that prep stuff.<br><br>I thought it could be interesting to use this technique with carpet pad scraps. If you had the right glue it could work and be all squishy.
if you wet egg cartons and put them in a blender with some glue you can make a really nice filler material-putty.
I'm surprised that this isn't featured... Good Thinkin'
Very cool, Excellent instructable and ingenious build<br>
This is so awesome! Im jealous of your daughter :)
dude thats epic. wish i was that skilled
Awesome job, you should be double happy.
Cool, thanks!
Cerveza Pacifico!
Wow! Someone has a lot of time on their hands!<br /> Great Project!<br />
What a lot of work, but the finished thing is great.<br /> <br /> L<br />
Thanks! Yeah, it was a lot of work. Early on in the project I wanted to know how much time it took, but about halfway through I decided to not record my time too precisely. I kinda don't want to know how many hours it took...
Very interesting, beatufil!<br /> <br /> Here in Argentina this project is not possible: all the cardboard is recycled by the &quot;cartoneros&quot; (cardboarders?) <br />
Thanks for the kind words. Argentina and &quot;cartoneros&quot; makes me think of gauchos wrangling cardboard boxes on the open pampas. <br /> <br /> I'm sure this type of construction could be done with many different types of materials, really anything that is available as a sheet or wide plank.<br /> <br /> A variation I've mulled over could use scrap carpet pad instead of cardboard. Find a carpet installer to get the pieces from and determine the best glue for the material and the sky's the limit.<br /> <br /> Shoot, you could make a chair as big as you want and just squish it through any doorway. <br />
&quot;Mad Genius&quot; from a teen-&nbsp; man that IS high praise!&nbsp; Way to go Dad!&nbsp;&nbsp; This is a very cool project, the jig rocks!
Wow! That looks great!<br /> If I&nbsp;could ever find enough cardboard I&nbsp;would so make one!
Well presented, the chair looks great!<br /> <br /> The jig and the use of cardboard is impressive. <br />

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