AAA Battery To AA Adapter

thingiverse

Uses M4 x 4mm Print with no support, brim would be good but not necessary. Put the M4 in the print (self tap) and slides it in the battery, might be a little loose or tight(depends on your battery dimension and print settings). But after you put it in your device, it will be clamped and wont move. Pro tip: Shorten the m4 slowly until the aaa batteries fit perfectly. The m4 could be inserted while its hot or glued to fix the position, but it is optional and not needed to function.