Wanted to try my hand at making a plate girder bridge (which are quite common around here). Since I'm printing with resin, build space is limited (and while I could print longer pieces vertically, the trade off in build time usually isn't worth it, unless I absolutely, positively have to).
Went with a modular design, so I could go as long as I want (as wide too if I modify it slightly). Along the way I learned a good bit about the construction of plate girder bridges (and the current design will be further modified, but wanted to finish what I started first.
This one has 3 sections and endcaps. Simple boards between sides, which in later versions will be I beams with boards on top (so the ballast doesn't fall down to the street). Total print time for the entire thing was about 16 hours, and maybe $10 worth of resin.