I designed this simple bit holder named 8yte, after finding only complicated designs on thingiverse. With 8 bits and 4 magnets inside it doesn't get to heavy while still holding the most needed tools.
It is one piece design with no need of support.
It takes 4pcs of 5x3mm neodymium magnets, which simply press fit in place.

For finishing I sanded them down to 400 grid wet. Letters were filled by 3D pen.

Update 21.07.19 Added some bevels at the hex holes.
New bit holder blank.step file without letters for personalization.

.step files included

Anycubic

All-metal Mega

No

No

0,2mm

25%