Hi,
pardon me asking, but why does it have to be 3D printing. I persume you plan in 1/32 or 54mm scale (Glossy?). In 3D you might encounter problems with the build chamber of a good resin printer. It will be rather expensive in anyway. FDM printers may work for larger scale, but personally I do not like the quality of that 3D printing process.
If you planning on fronts and buildings for Glossy Toy Soldiers than tin plate models would be the best choice. Staying true to the used materials - meaning gloss painted houses etc. to go with glossy troops will give the most pleasing and original results. Anything else is a bit like Ketchup on Caviar, if you know what I mean.
If done correctly, anything built in the traditional way such as using wood, cardboard etc. might work very well also ....
But that is just my opinion
good luck
regards
Wolfgang