I forgot to mention that I've used vintage car models for greebles; granted I haven't done a lot of greebling, but when I have, all those engine parts, grills, suspension linkages, and transmission system pieces have worked pretty well. Those kits can pack a lot of bits.
What is the best set of Legos to buy so you can use them to make walls for molds? I go to Toys' R Us and all I see are these weird sets that are all themed. None of them look like they had anything decent in them. Id have to buy over 100 dollars to build one small 8 x 8 box.
Is there a set or a place to get them for mold making?
Go to LEGO's web site and find the 'pick a brick' tab. I bought mine this way, I bought a few bases, some flat tiles, and several each of various basic bricks. They will ship them to your house. You can also build mold boxes with strips of card stock or sintra, be sure to cover the card stock with packing tape to make it smooth and none porous, then hot glue the strips together and to a base.
I wouldn't spend all that cash on Legos for mold boxes.
Go to Lowes or Home Depot and get some 1/4" MDF.
Cut it to shape.
Can also use thick foam board.
I agree, just use some simple materials first like wood, cardstock or foam core which works great, is easy to cut and cheap, the LEGO can add up.
Unless you have a table saw, the 1/4" MDF might be tricky to cut. Stick with stuff you can cut with a razor knife.
If you have access to a LEGO store in your area, they have a wall of bins of single bricks. A cup (not a cup as a unit of measure... like something that could hold 24 oz drink or so) full of them cost's 12 USD. As many as you can fit in there. At least that's what there is here (Portland, Oregon...)
Went to the lego store in Schaumburg Illinois in the Woodfield Mall. It was awesome. I ended up getting 2 x1 Building plates and a large cup and a small cup. Im actually having alot of fun just messing with them. I think I have to go back and get more...
if you're going to use legos - find used lots of them and buy a thousand or so.. some places sell them by the pound... buying them full price for mold boxes is a bit crazy - and I use legos