hello
if you want to use bullet script, I recommend particle simulation of CheetahBullet for it. so, I tried to make sample scene for dropping coins onto floor.
http://www.tres-graficos.jp/c3d/ch_coins.zip
it has 2 files, coins.jas is a scene using CheetahBullet scripts, so It requires an installation of CheetahBullet scripts. "Simulation" folder contains all objects for simulation ( collision calculation ), these objects will not rendered, just used for simlulation. In this sample, I used Cylinder primitives for coin collision ( Cylinder primitive is also used as collision primitive in bullet, so faster and more accurate than polygon mesh. ). and also Cylinder primitives are used for "CheetahBullet Particle Rep" ( object for showing simulation result of Particle object ), but If you want more detailed coin, please replace those primitives (NOT one in Simulation folder!!) to detailed polygon mesh, that has almost same collision size.
please check sample scene for more detail.
another one is no-required script scene, has particle object generated by simulation result for making still renderings.
demo movie is here:
http://www.youtube.com/watch?v=cvJ5KPrLx0g
please check it.
regards.
tg_jp, Hiroto.