Clip-On Library Shelf Divider with Label Ledge

Clip-on library shelf divider and book support with a built-in ledge for paper shelf labels. Prints flat in PETG with no supports, for roughly $1 of filament each. A small, springy hook clips onto the edge of a shelf so the divider stands upright next to your books and keeps them from falling over. A raised ledge along the bottom holds a label for call numbers, genres, or reading levels. I made this for a local elementary school librarian who wanted a lot of them. Store-bought ones run about $4.50 each, so printing them yourself costs roughly a quarter as much. It is an original model, not affiliated with any brand. Fit: modeled on a commercial clip that is rated for wood or laminate shelves up to 1 inch (25 mm) thick. The spring arm rests almost against the wall, so it grips thin shelves too. I have not tested every shelf thickness, so please check the fit on your own shelves. Print notes: print it lying on its side so the layers run along the spring arm, which lets it flex without snapping. Use PETG. PLA is too brittle for the clip. No supports are needed. Print settings: PETG, 0.2 mm layers, 2 walls, 15% infill, no supports. Size: the strip is 38 mm wide, the main wall is 158 mm long, and the ledge sticks up 4 mm. Wall thickness is 2.7 mm. Files: STL ready to print, plus the OpenSCAD source with all dimensions as named parameters (strip width, wall thickness, ledge height). Tip: print one narrow test slice first (set band_w to 15 in the OpenSCAD file) to check the fit on your shelves before printing a batch.