you need to make your own part for a model project. Or you
need to fabricate one part, and cast multiples of it so
they all are the same.
parts comes down to two basics:
You need to make the actual mold to cast from, which is usually
made from rubber or silicone. So you need those
chemicals. The mold allows you to reproduce your fabricated model
part many times.
You need to use resin to cast the actual model part,
using the previous mold you made. Once the mold is made, the resin
is poured into the mold. When cured, it's taken out of the mold.
takes practice to produce resin parts. You not only have to master
the resin casting, you have to master the mold making process
first as well.
vaccum chambers and pumps draw out the gasses that cause bubbles
- those will or can form on the cast part. The pump gives you
a smoother part, with a lot less chance of air bubbles and pinholes.
Two major things that will ruin a cast part.
are dozens of videos on youtube showing how it's done. It can
be fun at times because you can reproduce multiple parts that
all look the same, but you can also custom make parts for your
own model project. Which makes your model more accurate, or just
better looking than others who have built the same kit.
some cases you my need to replicate a part many times. If it's
something you scratch built the first time, it's often easier
(with less time and money) to replicate the part in resin.