How to Make an Arm Cast

How to Make An Arm Cast

(Please read through instructions and collect items prior to starting)

Download a printable version of “How to Make an Arm Cast” (pdf)

Items you will need:Needed Items

  1. Old clothes to wear
  2. Corrugated plastic yard sign (around $5 at hardware store)
  3. Sharpie
  4. Box/carpet knife
  5. Yard stick
  6. Duct tape
  7. Measuring cup
  8. Large bucket
  9. Whisk and spatula
  10. 7 cups of dried beans/rice or other small dry pour-able item (optional for step #6)
  11. Enough Buckets of Precious Impressions Memory Hands Keepsake Kit to cast arm (amount to be determined in step #6) From Amazon at


Things to know before you cast: The cast for “remote” Robohand fabrication must include all of the hand up to the elbow crease. This allows for custom hand cap and forearm gauntlet construction resulting in a more functional, comfortable and safe use of the Robohand design.

Step #1

Place arm that will be cast on corrugated yard sign from elbow to end of hand. Make sure lines in sign are running parallel with the length of arm. Add 1 inch past the hand. Use a sharpie and yard stick to mark this length. Cut off this end with a box/carpet knife.

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Step #2

Carefully cut slits every ½ inch or so in  just one side of the corrugated sign (Try not to cut all the way through the sign.) This will allow you to make a tube the length of the forearm and hand (plus 1 inch ).

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Step #3

Roll the sliced yard sign to make your casting tube. Make sure to leave 1″ of space on all sides around forearm (if appropriate, make sure tube is big enough to allow thumb to be held away from palm without touching side). Cut away any unneeded yard sign.

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Step #4

Tape over any slits that go all the way through the yard sign. Then tape ends of sign together using one long piece of  tape on the inside and another continuous piece of tape  on the outside.

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Step #5

Use tube as pattern on unused piece of yard sign to draw circle. Cut out circle and tape to one end of tube. This will Cap the tube, tape around and across to avoid leaks. If your tube is large you can reinforce it with a couple rings of duct tape to complete your casting tube.

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Step #6

Each bucket of Precious Impressions Memory Hands Keepsake Kit contains 7 cups of casting gel.

To find out how many Kits you will need:

First, place the arm your casting (up to the elbow) in the casting tube. Then fill the tube with 7 cups of dried beans, rice or other small dry objects. If 7 cups fills the tube half way you will need at lease two kits. If 7 cups fills the tube 1/3 of the way, you will need at least three kits, ect). Generally speaking, children will need 1-2 kits and adults need 2-3 kits.

Step #7

Follow Precious Impressions Memory Hands Keepsake kit casting instructions. With these modifications:

Make sure you have old clothes on.

  1. Place casting tube in large bucket to catch any overflow that might occur.
  2.  Moisten the hand and arm with olive oil before casting. There will be a good bit of suction when you remove the arm from the gel, the olive oil will help the arm slide out.
  3.  Find a comfortable position for the person being cast to hold arm, up to elbow( with thumb away from palm), in tube with bucket around for over flow.
  4. Set up for gel will take slightly longer than kit instructions. The more gel you use a longer set up time will be needed, around 3-4 minutes for an adult. The person being cast can tell when the gel has turned hard, the gel will turn from pink to white.
  5. You can use the “Precious Impressions Memory Hands Keepsake Kit” buckets to mix the gel and stone ingredients.
  6. When casting the stone portion of “Precious Impressions Memory Hands Keepsake Kit” start with very small amounts of “Precious Stone” making sure to bounce the casting tube up and down at an angle. Bounce in a complete circle, think numbers on a clock, to release any trapped air bubbles.  You want to get the plaster in every nook and cranny Note: If this is not done correctly, the result could be a cast that does not fully represent the individuals arm/hand.

Once you have finished your cast.

Please let cast dry thoroughly. Note: Casts will turn moldy during shipping if shipped wet.

Using a sharpie

1.) Write person’s name on bottom (elbow part) of cast,

2.) Write “palm” on palm,

3.) Mark where the wrist bends on both sides of cast !!! Do this by having the person bend their wrist then eyeball the same location on the cast . Don’t forget to do both sides!

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Step #8

Make outline of opposite hand to include with cast. Write name on outline. This is so we can provide a Robohand with as much symmetry as possible.

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Step #9

Print out and sign Indemnity form (UnderRoboforms).


Box up the dry cast ( pad it well for the trip), deposit check, Indemnity form and outline of opposite hand. Call  Ty at (888)445-2176. she will provide you with a mailing address.