Introduction: Helping Hands

Picture of Helping Hands

For those that can use an extra hand around the house!

I like to ask my students to think of some small thing in their life that could use a little extra assistance around the house. It can be small, from a toothpaste holder to a coat rack or an extra fist bump them when they finish their work. Then we make that idea more concrete!

  • What: Helping (Concrete) Hands
  • Why: Fist bumps forever
  • Concepts: Casting and Molding, Woodwork, Chemistry
  • Price Per Hand: ~ $2.50
  • Materials:
    • For casting:
      • Concrete (quick drying Rockite works great)
      • Alginate for the mold (I used this brand)
      • 2-liter bottle (or other large container for casting)
      • Mixing stick
      • A small piece of cardboard
    • For mounting:
      • Bolt
      • Threaded insert (that fits bolt)
      • Washer (that fits bolt)
      • Nut (that fits bolt, just for setting)
      • Wood
      • Screws
  • Tools:
    • Drill
    • Scissors (optional)
    • Utility knife (optional)
    • Saw
    • Sandpaper of Sander

Ready, Get Set, Concrete!

Step 1: Prepare Your Bottle

Picture of Prepare Your Bottle

Whether you just chugged 2 liters of Hawaiian Punch or scrounged from the company picnic, you've got to prep that bottle. Cut off the top with a utility knife or scissors, and then dry out the inside.

Put your hand in in the position you want your cast to make sure there's enough room so it doesn't hit any of the sides. If it does hit a side, you're going to need a bigger container. Time to chug 3 more liters of Hawaiian Punch! Or just use a box. :)

Step 2: Alginate: the Miracle Maker

Picture of Alginate: the Miracle Maker

If your mouth has been filled up at the orthodontist, or if you've ever dreamed of a purple heaven, then you know alginate well. Alginate is just amazing stuff to cast from living things. It's also neat that it's actually from the cell walls of algae.

Scoop some into your bottle that you think can surround your hand (a little less than half by volume), add water and mix. I used a brand called "Dermagel" from Douglas and Sturgess, and they recommend adding 1 part alginate for 1.5 parts water by volume, but I find that I can get good results by just eye-balling it aiming for a semi-goopy milkshake mix.

Get your hand in there! Once you've started mixing, your alginate is setting. For me, my hand got tired after a bit, so I used the side of the bottle to prop it up. To see if the alginate is set, wait 5-10 minutes and poke it to see if it feels like spongy but solid. If it is, you can start wriggling your fingers free and take it out. You can make it go faster by using warm water and keeping a higher powder to water ratio.

Step 3: Hand Out and Bolt In!

Picture of Hand Out and Bolt In!

Wriggle that hand out of there. If your alginate moves a bit when you take it out, that's okay! It's part of the magic. It'll return (ish) to its mold state.

It's bolt time! We're going to set a bolt into the back of the cast hand, but you're going to need a little support to do so. Make a hole in a piece of cardboard with some scissors (2). Then slide a wide washer on your bolt and poke it through the cardboard. Hold it in place with a nut (3), and make sure that the bolt will hand low enough into your mold to be deep in the concrete (4). Remember, the head of the bolt will be inside the concrete. You got it!

Step 4: Pouring Concrete

Picture of Pouring Concrete

Scoop up some concrete powder (I like Rockite because it's quick), and add water. Again you're going for a milkshake-like consistency. Pour it into your mold, making sure to move your mold around, angling it to make sure any air can escape from overhangs (like where my pointer finger curled in this mold).

Pour it to the top, and then place the bolt in the top. If you find the bolt is too far out, cut down the sides of your bottle until it's just right.

Step 5: Excavate!

Picture of Excavate!

This is truly the most fun part of any casting process. Is it a hand? Did it work? Will the fingers break off? Is there a live animal in there? It's just so much fun to go on the archeological dig of the most recent fossil on the planet.

After your concrete has set, remove the bolt and uncover your piece. (Look! The bolt is in there!) You can slide alginate out of most things, and then begin to peel it away with hands and scissors if you like.

And inside is.......YOUR HAND! AS A ROCK! IT'S A MIRACLE! (I really do feel this way)

Step 6: Wash Your Hand(s)

Picture of Wash Your Hand(s)

After you have a "HOLY MOLY, THAT'S MY HAND" moment or hour or so, you can start to clean up your cast. There will probably be little flakes of alginate, a few drips of concrete you don't like, and maybe some rough edges around the base.

I started with a a little water and a brush to take off some of the concrete dust and alginate, and finished up with sanding the corners around the wrist to make them nice and smooth.

If there are holes from air bubbles, you can always mix a little more cement and dab them in there. Concrete hand surgery is pretty forgiving that way. :)

Step 7: Make a Mount

Picture of Make a Mount

Your mount can be any shape you'd like, but I chose a circle. I used a roll of tape to trace around, and then cut it out on a bandsaw. I sanded down the edges, and then found the center of the circle for drilling.

My favorite method for finding the center of a circle is this one!

Step 8: The Threading Insert

Picture of The Threading Insert

This is a great little piece of hardware called a "threaded insert." It's adorable. It looks like a stumpy brass worm. It also is going into our mount.

Check the size of your threaded insert, and drill a hole slightly smaller than it in the center of your wood (1). Screw the insert onto another bolt of the same size (2), add some glue (3), and then use a drill to drive it down into the wood (4).

Now you have a great threaded piece of metal that you can easily screw your hand on to (5)! And you can trade out hands whenever you want.

If you want a more permanent hold, you can always do a more standard nut and washer method to hold the bolt in. If you do, just make sure to countersink them so they're flush with the wood.

Step 9: Saw Off Extra Bolt

Picture of Saw Off Extra Bolt

When you screw the hand all the way in, you may have some bolt sticking out the back. Saw it down so that you can mount it flat on the wall.

To remove the extra bolt, screw your hand all the way in and mark which thread you'd like to cut it off at. Put it in a vice, and hacksaw the bolt off, making sure to support the hand when it breaks free. Then you can either sand, grind, or file it down to flush, and soon you'll have a helping hand you can mount on the wall! Huzzah!

Step 10: Putting Hands on Walls

Picture of Putting Hands on Walls

If you want to put your helping hand up, it's easy to do! Screw the hand all the way in, and mark where "up" should be on the wood. Take the hand off, and then pre-drill two holes and insert screws. Drill them into the wall, making sure your "up" mark is facing upward. Then screw back on the hand!

Step 11: You're Did It! Shake Hands With Yourself!

Picture of You're Did It! Shake Hands With Yourself!

You did it! Your helpful concrete hand can be used for all sorts of purposes. Whether it's used as a coat rack or a high-five or a toilet paper holder or a guiding pointer, it's there!

I am excited to see what you all come up with, so do share below if you make one! Have fun and keep exploring.

Comments

Teen Librarian 1212 (author)2017-05-07

Could you please share how long you let the cement set up before removing the Alginate from around the hand?

Hey, good question! It can vary a bit depending on type, the mix ratio, and temperature of water, but usually 3-5 minutes should do the trick. It's quick!

I do it by feel which is to try tapping the surface and waiting for a jello-like density. At that point you can slowly wriggle free and escape your mold!

Sorry, maybe I didn't make my question clear enough. :) I'm actually asking how long you let the CEMENT set up before starting to remove the mold from around the cement. I've tried this twice, left the cement to harden for 30 and then on a next try 40 minutes, and the fingers break off easily in the process. However, I should note that I was using a different brand of cement - DAP quick plug anchoring cement - I couldn't find the Rockite that was recommended. Could the brand of cement be the difference or should I be letting the cement set up longer?

mrsmerwin (author)2017-04-10

I did this with my children's hands when they were little. The grandparents loved it.

jayawilliams (author)2015-10-27

I'd like to try this, though with a bit more forearm. I have somewhat hairy arms though... How does the algenate release from hair? (sorry for the weird question)

lime3D (author)jayawilliams2016-12-20

Coat your arms with vaseline first.

ruguberto made it! (author)2015-12-22

Hello nice instructable i made it in Colombia, i still have issues with the concrete but it went pretly well at first try thank you

helloperson (author)2015-11-29

Very creative and well written!!!

scavix (author)2015-10-26

F**k, this is brilliant! Need to make this for all of my family members. Will keep you posted...

CassieU (author)2015-10-26

They did this in the 60's & 70's. I think Cynthia started the ball rolling (so to speak):
https://en.wikipedia.org/wiki/Cynthia_Plaster_Caster

Sterlingrebel (author)2015-10-11

I'm so going to do this! Awesome! I'm getting rid of my Paris plaster "hands" I use for my jewelry displays!. I've never liked the look of them. Now I just need to find a narrow container long enough so I can incorporate the wrist and forearm too. Great work!

danfrain (author)Sterlingrebel2015-10-25

I think you can probably fit several bottles together to make it longer or deeper, if you will.

If they seem to be leaking, use duct tape or something similar to seal the edges.

Good luck!

You can use the core tubes used to ship carpet.

Carpet tubes? I'll look for those. I guess carpet stores might have some left over from jobs? Thanks for the idea.

Oh awesome! I'm excited to see it! You can build containers out of cardboard boxes fairly easily if you need! Just make sure to duct tape the edges up well!

I'll post ASAP!

manic matt (author)2015-10-09

I may have missed it but I would suggest can a metal coat hanger cutting it up inserting into the fingers just to add some strength to it. if you have a heavy set of keys it would break if you didn't help give it some strength.

dannynboyd (author)manic matt2015-10-25

Goid reasoning..

If you're worried about strength I would suggest using Fibermesh polypropylene fibers. We use it by the pound, per yard in concrete in residential and the steel fibers in commercial concrete floors. I have seen small packs of it for sale in Lowe's and Home Depot.

Hey manic matt! That's a wonderful idea for added strength. This one was able to hold a pair of boots on it, which is about as heavy as I need, but I'll bet it could be EVEN BETTER with some metal. Thanks for the comment! I'll try it out!

TomC57 (author)2015-10-13

I think I'll make one of my foot to use as a door stop!

Hey TomC57! I made an Instructable on your wonderful riff of Helping Hands! Now called "A Foot In the Door." I linked a thank you to your profile, but I'd also love to give you a pro membership. Would that be useful?

https://www.instructables.com/id/A-Foot-In-The-Door/

Now thats a cool idea...do u use it for a door stop?

cool idea! I love it!

cool idea! I love it!

That is just a phenomenal idea.

Greenman2 (author)2015-10-20

This is very cool wish I had the materials to do this.

dannynboyd (author)Greenman22015-10-25

Just go n buy it..they said it cost $2.50..and all the rest im sure u ciuld find around ur house..

TomC57 (author)2015-10-20

A Pro Membership would be great, thanks!

WYN soldier (author)2015-10-10

Why would anyone need something like that in their house. Its so creepy lol

I dint think it's creepy at all.......but I love art! Perhaps this type of art just isn't your thing?

Exactly!

francescavernuccio1 (author)2015-10-18

my son has had the same idea last year, he wants to do a handle for the gate of room his, but being a volcanic type with too much ideas for the head has confined to the plaster cast, never realized in resins

txadams (author)2015-10-15

Love it! It reminds me of the hand hat holders in the Willy Wonka factory.

nanaverm (author)2015-10-14

Tres cool! If you have an open hand position, could you make more than 1 hand per alginate mold?

xenia003 (author)2015-10-14

This looks really good! Definitely going to try it some time!

Eh Lie Us! (author)2015-10-14

Fist bump! who doesn't need this type of encouragement everyday?

LeslieGeee (author)2015-10-13

Thank you for responding so quickly and the info provided :)

ManifoldSky (author)2015-10-13

Used to do something similar back in the 70s with wax to make crazy, fist-shaped candles.

Jobar007 (author)2015-10-12

This reminds me of the scene in Willy Wonka & the Chocolate Factory (1971 version) where they go to hang up their coats and the hands on the walls move to grasp the coats and hats.

You usually have a cost per student listed with your materials list. Do you have a rough estimate for this project?

Oh great question Jobar. I find that if you go with the larger tub, it comes out to about $2.50 per hand. Not too shabby!

gstarr (author)2015-10-13

This is going to be AMAZING for our Halloween party! Thank you SO much!

Oh yay! That would be WONDERful. And handy! :)

LeslieGeee (author)2015-10-13

Hi, What a GREAT project and you made the tutorial simple and easy to follow :) I have one question about the alginate please. Since our hands do not have saliva to help make them slippery (eg. the dentist mouth casts) can a very thin coating of petroleum jelly or similar lubricant such as mineral oil be applied to the hand before inserting into the alginate to make the removal easier? Or would that affect the cast in some way ?Thanks :)

Hi LeslieGeee! Oh thank you for the comment, and this is a great question. Alginate does a pretty awesome job of being slippery enough that you don't need any extra layer on your hand. It'll slip right out from the spongy nature of the alginate. For casting, some people add soapy water to a mold before they pour into it (the concrete step), but these two materials are so different that it works out great without any additives. Have fun!

VanshM1 (author)2015-10-10

please tell me in which substance you had dipped your hand

Hi VanshM1! I used alginate, and specifically this brand: http://www.douglasandsturgess.com/category/BODYCAS...

It's amazing stuff!

Whoa, that stuff is pretty expensive. For $35, how many hands could you make from one container of alginate?

Hey wenestvedt. Thank you for the comment! And yes, it might be good to start with the smaller container (1lb) that sells for about $9. I found that it takes a little less than a 1/3 of a pound of alginate to make a hand. Have fun!

wenestvedt (author)wenestvedt2015-10-13

(P.S. Also, this is a really fun Instructable -- thanks for posting it!)

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