S-Scale Cold Storage Warehouse. A Scratch built building "flat" parallel to railroad yard tracks for a lineside business to load and unload railroad cars.
The Cold Storage Warehouse is mostly made from scrap pieces of plexiglass/acrylic window material of varying thicknesses that were obtained "free" from a local window/door business scrap bin. In addition commercial dimensional styrene strip and tubing stock of various sizes were used to construct window and door framing, roll-up door covers and some details. 
The scrap flat plastic pieces were measured, laid out and cut to size by scribing cut lines many times and then snapping along scribed line. Pieces, edges and shapes were finished by scraping, sanding, filing and some detail shapes were "carved" using files.
Parts were glued into sub-assemblies and and these attached by gluing with tenax/plasti-weld etc. to the main body, a larger piece of 3/16" thick plastic. The roll-up door openings were cut out with careful saw work and finished with 
filing. A stack of thicker plastic strips were cut and glued to make the loading dock adjacent to tracks. The top piece of plastic (the loading dock and warehouse floor) was cut fit into roll-up door openings. Any gaps that are to wide can be filled with plastic compatible p
filing. A stack of thicker plastic strips were cut and glued to make the loading dock adjacent to tracks. The top piece of plastic (the loading dock and warehouse floor) was cut fit into roll-up door openings. Any gaps that are to wide can be filled with plastic compatible p
utty and the entire assembly should be sanded with a very fine sandpaper, finishi
ng with strokes going in direction of beams and columns.
All the window and door Front and Back
frames as well as "roll-up" tubes are appropriately sized dimensional styrene, that was cut and fitted to surfaces and cut out openings. Then building and fire door windows were masked (very carefully and precisely - front and back) with tape (to prevent paint from covering).
Painted both sides of the entire warehouse with a plastic compatible gray primer, after a week to dry, other variations of grays and light beige's were misted over base primer coat to give a convincing "concrete" color and texture. Then all the trim was painted, and finally the corrugated metal doors were cut and fitted. The roll-up doors are HO metal corrugated tin (came in 4"x 12" size) mine are 'Suydam" an old HO manufacturer of kits, especially industrial buildings, also noted for their extensive "traction" supplies and rolling stock.
You can make a similar building and roll-up doors of any size you want. The opening size is determined by what would be going through opening (people, trucks, rr cars). BTW some plans have appeared in the model rr press showing how to make a working "roll-up" type door. It would pull straight up (flat) to simulate the action of a roll-up door.
