I've printed these with 0.20 mm layer height and a 0.4 mm nozzle. Breadboards are attached to the holder by sliding them in. Remove any adhesive pads from them first. The breadboard should stay in place fairly tightly, but if not you can use a bit of glue to help.

Make sure your breadboard's width (not including possible “extension” points) matches with the description of the file you download. If not, tweak the breadboardWidth parameter in the attached Fusion 360 file.