You need to print 2 of the “end” models and one of the “middle” models to get 8 “bits”. The three models will slide together to create 8 bits, one byte. Print at 0.3mm layer height. No supports needed.

Each bit fits one of these Portabulbs from Litezall. The Portabulbs use batteries and the bottom is magnetic. 

Pause the prints at 1.2mm layer and insert a steel washer into the “hole”. The print will continue around the washer and enclose it providing something for the magnet to attract. Use washers less than 2mm in height with a diameter less than 28mm.