You can use this model as a counter or countdown. It has a hole in the back to set the numbers correctly, e.g. if you want to start a countdown from 50.

I printed all parts except the spring with a layer height of 0.2mm and a filling of 15%. The spring with a layer height of 0.12mm. Almost all parts can be printed without some but with little support. The printer must have a clearance of 0.1mm.

Instructions:
1. Put the spring in the button. And the gear wheel into the rotator.

2. insert the rotator into the button holder and insert the button with the spring from the other side.

3. put the 4 gears (planet_gear_top) into the holes and then put the rotator (outergear_top) over them.

4. now place the middle case.

5. insert all numbers into the number holder (pay attention to the direction) Depending on whether you want a counter or countdown, you have to place it the other way round. I have made a counter.

6. now place this in the case.

7. if you only want to count from 0-9, press the bottom cover (case_bottom) on it now, otherwise the middle piece.

8. Now attach the case_top.

9-11 Only for more than one layer.
9. place the planet_plate_middle and the sun_gear_middle_1 and the 4 planet_gear_middle_1 in the holes. Then place the two outer_gear_middle1/2 on top.

10. put the 4 planet_gear_middle_2 and the sun_gear_middle_2 into the rotator_middle and then join them together with the part from step 8.

11. then put the case on top again, numbers in the number_rotator and case_bottom or centre piece on top.

If you want more layers, simply repeat steps 8-10.