More plastic casting with Composimold

Among other things, today I made some doll parts for a pug-sort-of-creature toy that I’m making, and used some “leftover” plastic from casting those parts in one of my skull molds (a teenage Chinese girl) and made myself a skull bowl using an old t-shirt and some ribbon to line it. Here it is, and there’s lots more (including some step-by-step on the mold making with Composimold, which is very cool stuff so far) of that project and some stuff that Nefarious is working on after the break.

So yeah, more after the break.

I started by making some parts for the stuffed toy out of Sculpey; a nose, an eye (which gets cast twice), an an upper and lower tooth-filled jaw, and a credit label/tag that I likely won’t use. I mounted these parts inside a box made out of thin packaging plastic and sprayed it with mold release. The Composimold is really easy to prep — just put it in the microwave for a minute. Once it gets about half as hot as boiling water (so not particularly hot) it starts to melt, and eventually it has the consistency of thin syrup. It’s very easy to work with and seems quite resistant to bubbles. I poured that into the plastic box and then stuck it in the fridge to accelerate cooling.

After the material hardened to the consistency of hard rubber, the original parts popped right out. I’m qiute impressed by how amazingly easy this all is to do.

Now that the master pieces were out I was ready to make the parts. I sprayed the mold with mold release, and since I knew I’d have some leftover plastic, I also sprayed one of the silicone skull molds I’d made. I mixed the plastic 50/50 by weight in an old chickpea can from last night’s supper, Even though that’s a big piece, it’s still hardly any plastic and very inexpensive to make because it’s hollow. Anyway, I poured the plastic mix into the open top mold, and then into one half of the skull mold. I quickly added the other half of the mold and taped it all together. For the next ten minutes or so I slowly sloshed the plastic around and twisted and turned it to make sure that the plastic was evenly coating the inside. In addition to the heat from the chemical reaction, I knew it was working from watching the stuff in the open mold. It’s pretty cool looking — the below animation takes place over around thirty seconds:

Sorry about the 600k.

The first set of teeth that I made had bubbles in them so the teeth don’t have tips and look jagged and rotten! But the second time I did it I poked the teeth with a wooden skewer to make sure there were no bubbles and it turned out perfectly, so now I have the parts needed to make the toy. The best part is that if I don’t need to make any more of these parts (and unless someone tells me they want some for their own projects, that’s likely) then all I have to do is reheat the mold material and it will melt and I can cast something new! Meaning, it’s now effectively free for me to this stuff, and you can’t go wrong with free!

The skull as well turned out nicely, although there are shortcomings in the mold itself (the silicone had bubbles, and I didn’t really put much effort into getting it perfect since originally it was just intended for wax) that I needed to correct with a Dremel. As I mentioned, this plastic machines beautifully. Also, since I cut the top off, you can see that my rotation of the curing plastic worked nicely and the skull has a quite even thickness all around and is of course waterproof.

As you know from the opening photo I lined it with an old t-shirt and then glued a ribbon around the edge to make it look a little cleaner. The photo doesn’t do it justice. It’s on my desk now as another small, general purpose bowl. I’m very happy for it, and as I mentioned, it was basically free to make. I just love making this stuff, and it’s so incredibly easy. I’ve been thinking about offering Nefarious’s teacher to come in and teach a mold-making class to the students. It’s a mixed class of grade one through three and I think they’d love it.

Speaking of Nefarious, she’s been working on her own project, a pair of crutches. I’m not sure where she got it in her mind to make them but she built a prototype out of foam and then had me cut them out of wood, which she finished off with foam and fabric. She did this work while we read Gifts, which is quite good so far and very dark.

So now she’s been hopping all around the house, matching my cane I guess. I’m now no longer the only cripple under these skylights.

Anyway, tomorrow morning I have a first-thing-in-the-morning doctor’s appointment, so let’s hope that goes well. I really need it to. As I mentioned, the biggest reason that I’ve been doing so much stuff is that the second I slow down, the flames of my circumstances catch up and continue burning these aweful charred painful stumps that I’m forced to walk around on as they slowly turn to charcoal. So, good luck to me, because I’m out of endurance for this hell and I’d rather keep on casting plastics than tying hangman knots. Just kidding?


  1. Augustus wrote:

    Please send me that awesome skull. I need to take more of your approach to making things :)

    Tuesday, January 25, 2011 at 9:12 pm | Permalink
  2. lish wrote:

    ok. i need a skull box for joe’s next birthday. please to be making this & let me send you money for it.

    Tuesday, January 25, 2011 at 9:13 pm | Permalink
  3. MONTE wrote:

    did anyone else notice Nefarious flipping off the camera in the first crutches picture?

    Tuesday, January 25, 2011 at 11:52 pm | Permalink
  4. Twwly wrote:

    Wow, she looks so extra big now, big kid tall. Time goes fast.

    Love the dog toy parts, looks like you are sculpting Puppers, haha!

    Wednesday, January 26, 2011 at 8:39 am | Permalink
Wow Shannon, that's really annoying! What is it, 1997 on Geocities? Retroweb is NOT cool!

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