Printing didn't take long, even at .1mm layer height. Infill was 30%. On the next print I will increase the top layers to 7, instead of 5, since the printer wasn't able to create a completely smooth top surface. It would probably work just fine it the infill was higher - like 50%.
Since I'm printing on a glass surface the bottom was pretty smooth. I made good use of a knife to make more grooves to be sure that the Sugru had plenty to adher to.
Printed the "Thumbs up" on a secondary printer. The depth of the relief could probably be half as deep in retrospect. In this one it was 2mm deep. That would make it easier to keep fine details when separating the mold from the stamp.
Note to self: don't mirror the print. Since we are making a positiva - the stamp will be automatically inverted for you.
Make sure the Sugru get plenty of time to cure. I left it a couple of days since we didn't have the ink-pad yet.
Not perfect, but enough to show that the principle works. The ink doesn't adhere extremely well to the stamp, but that might hopefully change over time as the surface get roughened up. Maybe using some fine sandpaper would help as well.
The stamp handle and "thumbs-up" model can be downloaded here: