I enjoyed reading about your trestle adventures. I have built several and have used the following method for my jigs: I build one full-length bent using a paper plan covered with a sheet of waxed paper. Once the bent is complete and I am happy with it, I lay it on a sheet of .030 styrene and carefully draw the outline of the bent onto the styrene with a pencil. Then I remove the bent and glue tiny pieces of strip styrene to the styrene sheet along the pencil lines using liquid cement. Once everything is dry I can glue my pre-cut pieces of wood together. I have used white glue successfully and have never had a problem with it adhering to the styrene. I also end up with a styrene jig smaller than a piece of typing paper which I can store vertically in a file drawer for future use. A photo of a jig is attached.
I have attached two photos of my creations. One is a trestle that is installed on my layout, a free-lanced logging and mining line named the Tabernash Lumber Company (named for the town of Tabernash in the Colorado mountains.
The second trestle is a free-standing diorama. I wanted to model a trestle under construction, but had a devil of a time finding any helpful period photos! Almost every old photo I found showed completed trestles, so I finally freelanced what I thought a trestle under construction might look like.
Thanks for the update. Share this with you. I made a jig by pouring a 1/2 thick or so bed of plaster into a plastic lid from a to go container and pressed a completed bent into it to create a mold. Just lay your pieces in the depressions and glue away.
Getting redwood twigs on my walks and liking the results. I don't think loggers took the time to skin the bark off of trees so pretty prototypical looking I think.