Although I've done this before, it certainly helps that my live-in partner Isabelle has an MFA in sculpture, so she can give me tips and advice and pretty much any tool or material from her studio for me to play around with. The really funny thing is that she's borderline traumatized over mold-making from her academic program (high stress and giant molds that likely break a months-long sculpture!), whereas for me these little jobs are a delightful break, and each step is doable in about 20 minutes or so (although there's about 20 steps in my checklist now). Here's a few photos from the weekend that I cast the frigate copies:
First, the very start of making the mold for the Sathar Frigate. I make a little box out of posterboard (cut to save as much material as possible): half of it gets filled with play-dough, and the original mini gets embedded in that. A good pour-hole/sprue is definitely the most important part of the process (I would improve on what's shown below for another attempt). I pour in rubber compound over this and let it set for the night; then I flip it, dig out the play-dough, and set in rubber to the other half over another night.
By Sunday, I've got three molds ready to go (one Sathar frigate, one UPF frigate, and one for the bases they get mounted on). Below, we're about to get ready with a block of metal in the ladle. (Note to self: in the future don't keep molds waiting on the stove, you don't want them heating up unnecessarily.)
Melting the metal on the stovetop.
Here I am midway through the casting process, with one UPF frigate already cast and new ones just coming out of the molds. It was around this time that Isabelle came home from her studio, with me bent over the table and metal bubbling on the stove, to which she expounded something like, "My god, you've turned our kitchen into a foundry!" (which was delivered with more delighted glee than you might expect).
One funny thing is that what's classically my favorite spaceship design -- the Sathar vessels like the frigate here -- turned out to be a total nightmare to cast and get out the mold. Those spindly little engine and neck struts would inevitably break off when I tried to take them out, snap off the sprue, and straighten them. I think I probably cast at least a dozen Sathar frigates, but most of them got broken and dumped back in ol' the melting pot. (Again, I'm pretty sure a change to the pour-hole design would help this a lot.) At the end of the day, this was my production line. Probably more on this later if anyone's interested: