Marble Exercising Machine - Part 8 - Piston Engine

This part of the Marble Exercising Machine is the Piston Engine. It is a stylised version of a side-valve straight six engine, without the cylinder head. The valves are just for show.

The components needed are one of each of the above stl files except:
Piston - 6 off
Exhaust cam - 6 off
Inlet cam - 6 off (note that the inlet and exhaust cams are different)
Cam follower - 6 off red (exhaust) and 6 off blue (inlet)
Valve head - 6 off red (exhaust) and 6 off blue (inlet)
Thin s