This solder roll holder for the gridfinity system by Zack Freedman (https://thangs.com/designer/ZackFreedman)  only needs 1x2 gridfinity slots (and a tiny bit, the shaft is 44.5mm long) and is able to hold 2 rolls of 100g solder rolls, e.g. for a 1mm and a 0.5mm roll of solder. There is however a version for a single roll of solder as well. The inner distance limiting the thickness of the rolls is 36mm.

The inspiration campe from a solder stand design by CalcProgrammer1 who designed thing:5952889 on https://www.thingiverse.com/thing:5952889

However his design uses a 2x2 grid and is intended for a single roll of solder. So I used the Gridfinity block template @FilipKolinsky_352287 

If the hole of your solder rolls are big enough I recommend using the 18mm version, if you have a roll with a smaller diameter you can use the thinner shaft provided or you can simply scale the shaft down a bit.

I suggest to use quite a bit of infill for the stand itself, otherwise the parts might break too easily. I only used supports inside the magnet holes. I have not installed any magnets, it is stable enough without them.