I remixed the original to use an M3 25mm screw to hold down the item being soldered.

Printing
Best printed in Petg for strength.  Originally, I printed this in PLA but it broke.

Remixed
https://www.thingiverse.com/thing:2900194

Bill of Materials
1x M3 25mm screw or longer
1x M3 18mm screw or longer
2x M3 washers (optional)
1x M3 hex nut
1x M3 nylon hex nut (can substitute an M3 square or hex nut)
1x Spring 8x20mm