Meanwhile I made the little studs that connect the seat to the frame. I soldered them in place after marking the position on the frame. With some papertape -there was no ‘third hand’ at hand…- I held the studs in place. Adding just a little bit of tin in the beginning allowed me to adjust the angle of the studs to make the seat feat neatly in place. Afterwards I soldered the studs all the way around to fix them in the right position and angle.
I also glued little pieces of PLA wire to the seat with superglue, these little pieces fit in to the studs on the frame.