For now I use 9/16" diameter precision bearings (pinball size, can be purchased cheap from Lee Valley) that I sandblast and primer flat grey. Then, I get small 5mm diameter neodymium magnets from Walmart, as they are the ones found in the little fridge magnets they sell. I just crush the plastic in a vise to get the magnets out. This is the cheapest way to get a whole bunch of magnets I've found.

Precision spheres are great because as you may have found, you can't scan bolt holes. If you place a sphere in the hole, not only will you get a nice clean scan, but with that sphere you can find the exact center of that hole every time. The more accurate the sphere, the more accurate the hole.

In this case, precision bearings are about as accurate as you are going to get, and they work great for this scanner. I made a whole bunch and they really show when the scanner is accurate and when it isn't. As it get far in the distance or close to the sides you can tell by the spheres if the data is right. Luckily with other software I've been playing with it can automatically tell you how much the points are deviating and you can start to make a more informed decision about what you want to keep in your scans. Long term I think it would be nice if we could get the Einscan software to detect this for you so the scans are highly accurate everywhere.

We'll see. As for the reference base, I would flip over a mirror or take a sheet of glass and paint it flat black. Then maybe paint some flat grey stripes on it or some sort of pattern, you want the pattern to be non repeating and to have probably less than 10% coverage. The more grey you have, you more points will be generated each scan that hits the surface. Since the surface is flat and you have the spheres for positional reference, you don't need much grey at all on the flat plate.

I hope this helps everyone.

Dave @ Nerv