The ISU 'Scorpion' chassis with adjustable traction magnets
This is the second 'proof of concept' chassis, dubbed PS2 and in metal, as sent to, and lost by, Tom Lowe
Here you can see all that made it to his 'version', the holes for the allen key!
More images of the PS2
This is the original Scorpion 'proof of concept', machined from plastic