I got started in casting 9 years ago now and always find new and interesting challenges. I started out with the paint on latex molding stuff for about 1 week and realized it was way too time consuming. I then ordered my first 1 gal bucket of silicone rtv. I also ordered a 2 gal kit of polyurethane resin. I found myself molding all sorts of things that I could use more of on my display table. What a great way of learning even tho it was probably the more costly way to go.
The main thought to remember is in gravity casting the resin goes down but the air has to come up. I had lots of problems with trapped air bubbles but you soon learn how to place an object and how to make vent holes etc to eliminate problems. Even filling in gaps with a thin piece of styrene to allow the mold to not touch allows air to escape. Later it just gets cleaned up on the parts.
I have had good luck with the various brands I have tried. Each product has its use too. Some resins are thin like water, some are like syrop.
I have yet to try clear resin on my own projects but it is a bit of fun to work with depending on the brand and type.
Some brands website links and help tutorials are : (products I have tried)
www.alumilite.com (resin)
www.polytek.com (easyflo 60 resin)
www.smooth-on.com (smoothcast 300 resin -cures white) (Mold Max 30 silicone rtv)
www.silicones-inc.com (GI-1000 rtv)
www.synair.com (mark 2 resin and rtv)
Rhodia - V-1065 rtv and (ViSil 2025 - discontinued in canada but was superb)
I have yet to get into metal casting into rtv or otherwise yet but there are some people who do it.
Kent, Manitoba, Canada