A saw a similar device in a thread on rivets and since I have acces to a workshop (working in a factory has its advantages) I decided to create one.
ingredients : some scrap plexi (thick) 2 bolts and wingnuts, assorted drills, scrap iron rod and a lathe and a piece of 1mm thick electrode rod.
after cutting the plexi into 2 equal parts I wrapped some tape around it so they would remain in place.
I then drilled 2 holes (6mm diameter) for the bolts (M6) to fit in.
screwed the wingnuts on and tightend the lot.
next step was drilling the holes. I went for 1 / 1,5 / 2 / 2,5 / 3 / 3,5 / 4 / 4,5 / 5 / 6 / 7 / 8 / 9 / 10mm
On the Lathe I turned matching pins. (Well, at least for 3 / 3,5 / 5 / 7 and 8mm)
for 1mm I use the piece of electrode.
I'll have to look what to use for the other small diameters and I still have to make the other large pins.
and this is what it all looks like :

and here with some punched out styrene sheet :
