I found a bit of hex bar which i turned down one end and threaded it UNC to screw into a water pump bolt hole drilled and tapped the other end to take the pointer doo daa which I cut and hand finished. I then turned a boss up to fit on the crank nose, drilled and tapped a couple of holes then bored a hole in the disc then two slots for movement, which I did by chain drilling and hand finishing again ( my milling machine is NFG at the moment).
The way you use it is quite decent really, you set the engine to approx TDC and bolt the boss on, fit the main disc and bolt that to the boss using the wing nuts do the old 10 thou before and 10 thou after bit using a DTI gauge as per normal find true TDC, do the calcs,undo the wing nuts, turn the disc to zero, do the nuts up and off you go.
Shooter