Decade Resistor Box

Decade variable resistor 0 - 9,9Mohm* in increments of 1ohm with a 3d printed enclosure using moderately cheap and easily sourceable components.

Total cost for the parts orders looks to be just under 20€ The soldering is rather tightly packed, so proceed at your own risk.

A note about resistor tolerances: I'm using 1% resistors. I wanted something better than the really cheap and common 5% resistors, but much better than 1% costs too much. Also, the switches themselves add resistance and some variance. The tolerances don't add like some people worry for setups like this - any resistance I can dial in will be within 1% of the number on the switches - in theory. The switches add a couple ohms (1.5ish) to the box overall, so the low values will be more imperfect than the high values. Also, it's best practice that once you tune a circuit with a box like this, you remove the box then measure the resistance instead of relying on the readout.