This installment is more for those who are just starting out who want to learn about resin casting. More experienced model makers know all about this, and more.
If you are thinking of building a studio scale model, you know you have to get your hands on some very rare, hard to find, and very expensive kits. It is important to learn how to save time and money by copying parts you need more than one of.
I just got in the mail one of those rare kits. It comes with two small parts that my Star Destroyer needs 20 of. So, those two parts, plus others are currently in rubber.
I never played with Legos as a kid, but they come in handy when you need a customized container to hold the silicone mix. This way you can build a reusable container to suit the part(s) you are casting so you are not wasting rubber. This is a tip I read somewhere, and this is how I cast all my small pieces.
I use double-sided adhesive sheets, cut to size and stuck to a throw-away piece of plastic. I then stick the parts to be copied on the adhesive, leaving enough around the edges to stick the Legos to it as well. The adhesive keeps the parts from floating in the mixture, and seals the containment area, or silicone will leak from underneath. It is also cost effective to cast as many different parts at a time.
The Alumilite brand I'm using here requires a 10 to 1 mixture of rubber and catalyst to cure properly. The resin requires 1 to 1.
Before beginning, it's important to prep the parts being cast. The Star Destroyer uses multiples of this 8-Rad part (many filming models of that era did). This part, below, first had to have its sides removed with a hobby knife or saw. It also has many openings that have to be plugged up. I noticed the outer edges on this part are higher than some details in the middle, so it doesn't lay flat on those edges. It was necessary to build up the outer edges with plastic so they were higher than the inner details.
Depending on the cure time of the silicone you use, it could take a day or a few hours before you are ready to cast pieces in it. The pink mix will take about a day, but for this 8-Rad part I used the yellow mix, which meant I was copying it the same day. The pink mold is softer and more flexible than the yellow. They are both durable, and will last through many castings before they lose their usability.
A good thing about resin castings is that they are easy to work with. If you haven't tried it yet, resin takes a mere 3 minutes to harden, so you don't have to wait long to have all your needed pieces.
There are experts here in dealing with resin that have more advanced ways of doing things, pressure casting, etc. But if all you need are a few parts using a one part mold, or you just want to learn the basics, this could be a good starting point for you.
Hope this helps those who always wanted to try it!