I have played "Powder Toy" for a few years before this, and I did like their moving solids, and yes, I agree that they would be a nice thing to have, but if you haven't noticed that in "Powder Toy" these "moving solids" are glitchy as well, when working with them myself, I often found that the structure I was making would - for lack of a better term - settle, and no matter how many "joints" I added it would still settle; This was often very annoying, and while we're on the subject of "Moving Solids in TPT" why don't we take a look at jacobs mod; I have the mod, and I do think it quite interesting; but, when it comes to the "Ball" I dare say that even that isn't the best thing in the whole world, for example, it seems to sink into elements it collides with, so really, smoothly animated moving solids are currently beyond the current stage of TPT development. Personally, I think that even The Powder Toy is losing interest, and just as a suggestion; Why don't the developers - whoever they may be - add some more, "Interesting" things onto TPT, just to stir things up?

I still think BALL has room for improvement though.

by the way, if you think a suggestion isn't worth your time, throw it at me, my mod needs more stuff.

I swear it hasn't got moving solids. Other than BALL and BOX and WHEEL. But I think that was only in the first powder game, I played the second one (although I did play the first one, too).

You can make moving solids by just using tpt.el.[element].loss=1 and then setting vx or vy of that element, so why not in the regular game?

Hmm, well I looked into what DanBall had. Apparently some actually pretty interesting softbody polygon/edge-based mesh. I tried designing something for my own program last year even with rigid bodies had some difficulties programming the separating axis theorem and figuring out how to determine collision points and produce accurate collision responses. Constraint based physics simulation has been a problem I've been trying to figure out but never really got to for some time. Either way if I hadn't occupied myself already with so many planned projects and ideas, I would be happy to look back into that kind of processing, and try to come up with something and provide some source code as I might be also programming some rigid and soft body physics in a 3D physics game I was planning.