JJ-CCR counter lung 75mm spanner

75mm spanner for servicing the JJ-rebreather counter lungs. Add a M3x15 hex socked head screw (about 5.5mm head diameter).

Use together with https://www.thingiverse.com/thing:7334117
Can be printed without supports. I printed with PETG-CF (6 walls and 50% infill).