Abacus (with Tutorial)

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Abacus: no support, brim, 10% infill

Marbles: no support, brim, infill 100%

Sticks: no support, brim, infill 100%

(alternative sticks of your choice with 3mm diameter, length normal 183mm, small 123mm) 

Construction:

One abacus needs 10 sticks and 100 marbles (10 per stick) preferably in at least 2 colors. 

During assembly, you should hold the marbles on the stick with a clamp.

At the end, glue the sticks with superglue.

Tutorial to use an abacus. Link: