The Freshette?
I measured it. The flexible tube part is slightly curved and is about 5 1/2" long and 1/2" thick. It can be slid up and out of the pink pee-cup part.
The pee-cup part is about 4 1/2" long, 1 1/4" wide at the widest part (more like 1" up at the front) and from top to the little spout part poking out in front (it's 'tallest' part) it is about 3" tall.
I don't know anything about making STPs, but hopefully that info can be interpreted with someone who's more experienced with it.
Edited to add: Er, that is STP+Packers, to clarify.