RAW, it seems you are limited only by your budget, similar to how you could craft as many power stones as you could afford (and traps aren't particularly cheap).
Possible issues? Storing them for use, if you have 200 traps sorting through them to find the right one could be problematic. Or if you have them in a bandoleer or some such, they become a target by intelligent opponents.
If it becomes an issue a safe "rule of thumb" would probably be something like 1 per level (similar to how you can have one psionic tattoo per ML).
What was the name of the post/thread, didn't see anything on the page that came up from the url.
That's a good question. I'll get back to you on it. Need to review notes and prior discussions.
I know Jeremy is busy with the kickstarter, just bumping!
So based upon what I'm looking at, the budget is really the only limiting factor, similar to if you wanted to get a scroll of every spell possible.
As for the physical details - a folded trap is roughly the size of a dagger (since just saying it's the size of a rock doesn't really give any sort of point of reference.) Small enough to hold in the hand, large enough to throw a decent distance without needing some sort of implement like a sling. It would essentially look like all the component parts of the trap collapsed in on itself.
Thanks Jeremy.