sdandrea1 My son is into 3D printing and we've been talking about making a putter head.
Cool ,3D printing is a lot of fun and very rewarding when things turn out the way you planned.
As far as head weight,I always use brass, it's easy to drill,cut,machine and it usually has enough weight to
get you where you want to be as far as total grams.
Also when 3D printing, in your slicer program use 100% infill, that will add quite a bit a of weight to the head by itself.
What I'm trying do is add the weight/brass to the head as I'm printing...ie use a cad program to leave a void in the head,hit pause on the printer, add the weight and resume the printing so the weight becomes part of the 3D printed head.
You can also purchase metal impregnated filament, but it's not cheap.
Good luck!
