This parametric cap generator was originally designed to produce simple lens caps. The cap can have an eyelet or not. As it is parametric, you can generate caps for other devices Open the .SCAD file with OpenSCAD, adjust the parameters, save and press F6. Then export to STL. To remove the eyelet, just set eyeletDiameter=0; A 49mm / 5mm deep .STL is provided as an example Feel free to modify this thing at your convenience. Good design is hard work, donations are welcome.