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I've been thinking of making molds of body parts (limbs, torso, head, etc) that could be connected with wires and posed. That would make customizing minis a bit faster. I was wondering if anyone else had done that. I couldn't find anything by searching, but I could be using the wrong terms. If anyone's tried it and has any tips, photos, or can link to a post, that'd be great. Thanks!

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Were you thinking of metal casting or resin? I've done a bunch of resin casting for myself over the years. Mostly it was as a cheaper way to maximize bits usage from GW boxes but I did do a few custom bits that I wanted multiples of. I also made and sold some movement trays and bases for a bit. The only metal casting I've done was drop casting bullets for muzzle loaders years ago. I don't have any pictures of what I've done on this computer but could probably get some in a few days.

 

What I started with was a resin casting set from Micromark. It gives you all the basics you need to start. When I was making movement trays and large bases I was buying mold silicone and resin in gallon jugs from Smooth On. If you do a search for making two part silicone molds and resin/polyurethane casting on Google you can learn most of what you need to know. For small bits like you mentioned you can make a mold using Lego bricks. I haven't made any new molds since I learned about that but it sounds way better than the boxes I used. Here's a quick tutorial from my experiences.

 

Making the mold.

Find a box or make one out of Lego that is a bit larger than your parts you want to cast. You don't want the mold to be too thick or it's a real pain to remove the cast parts. You need to try and find the balance between thickness for strength and thinness for flexibility in the finish mold halves. I try for a bit less than a half inch of mold on each edge around the pieces. I pack the modelling clay in the bottom of the box making sure it (the clay) is deep enough to push the pieces into it half their thickness. You also need to think about how the resin will flow through the mold as you pour it. Most often I do molds of arms or heads with two arms/heads in one mold. Bodies are usually big enough I do them one per mold. I aim for a U shape with the bits I'm going to cast as the vertical arms of the U and a chunk of sprue/ bamboo/ whatever making a channel between the bits on the bottom. I also add a piece of sprue/bamboo coming up from the bits to what will be the top edge of my mold. To help with mold alignment you can add a bead or some other small object in the corners.

 

One of the trickiest parts for me was figuring out how much silicone I wanted for the mold. The method I used most often was guess and throw away any excess that I mixed up. Later on I poured water into the box up to the level I wanted and measured how much it was. Trouble with that method is you need to dry everything thoroughly before pouring the silicone. Once the box and bits are ready paint or spary the clay and bit with mold release. Then mix your silicone according to instructions and pour until the highest part of the bits is covered by the about a half inch of silicone. Too little and the mold will tear when removing your casts. Wait however long is necessary for your silicone to cure (mine was 4 hours). Carefully remove the silicone and bits from the box and clay. Sometimes there's a bit of seepage around the bits. I take a sharp razor/exacto knife and trim that so the first mold half is as level as possible around the bits. You can remove the beads from the corners now and this will give you matched bumps and holes to align the two mold halves. I place the first mold half back into the box with the bits facing up. Sometimes the bits pop out of the mold when doing all of this but I just push them back into place. Paint/spray everything with mold release and pour the second half of silicone. The amount should be the same as the first half unless you have a piece that protrudes a lot more on one side. Once the silicone cures you usually have a complete block that you can't open. Carefully find the seam between the two halves and if necessary cut it open. Remove the bits and check to see if the resin can flow through the mold. There's often blockage in between each of the sprue and bit pieces. Very carefully trim out the blockage. This should give you a usable mold.

 

Casting

Prep the mold by dusting both sides with talcum powder or corn starch or use a spray release. Make sure to shake off all the excess powder or it may obscure detail. Put the mold halves together and place a piece of wood or other hard, flat object on either side. Secure the pieces together with rubber bands or tape. The resins I like to use harden pretty quickly so I don't have much time if I mess up the next steps. I use medical syringes for measuring and injecting/pouring into the mold. Because the bits I cast are generally so small I set up several molds and sometimes have something in an open one piece mold to use up any extra resin. I measure each part of resin in a separate syringe and then mix them together quickly. Usually I use 10-15 ml of each part which is enough to make several complete 28mm minis. When things work right you can make a ton of bits or minis for almost no resin. I use a third syringe to suck up the mixed resin. I tap it and try to get rid of any air bubbles in the syringe the same as you would do before injecting an animal or person with medicine. I then inject the resin into my mold holding the mold so the air can escape out of the upper end of the U. If I know there are feet or other protrusions on one side of the mold I try to have that side more downward so they fill better. I inject resin until is starts to come out of the second hole. I then tap the mold on the table a few times to shake loose any air bubbles. Then I inject a little more resin to push those bubble up into the channels above my bits. I don't have a vacuum/pressure set up but have fooled around with a vibrating table to help get rid of bubbles. Most of the time I don't feel it's really necessary but I'm ok with patching the odd bubble or resculpting feet on minor miscasts. What until the resin is cured and then carefully pry open the mold and remove the bits. If the mold was held together tightly there should be a minimum of flash that can often be removed just by brushing it with your thumb. If it was too loose you can end up with thick mold lines needing a lot of cutting and filing to remove.

 

OK that ended up taking longer than I expected but I hope it helps. If you have any specific questions just ask and I'll try to answer. Overall resin casting isn't real difficult but it can be a bit time consuming. I think the trickiest part is designing the mold layout for the least amount of effort and best results.

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