
Mount the piece in a chuck and drill.....


Make a peg from an old 5/32" drill bit....

Drive it in and Super-Glue it....

Drill and notch a 2p coin...

Fits tidy 'cos the 'slot' is actualy a quadrant of a circle the same dia' as a 2p coin...

Jobble done, Tamper-proof DZUS


Now, all I need is a seat cover to replace the one that went AWOL last week.
