Quick and dirty 5 minutes craft: Draw a rough shape, define the contact surfaces & load, click run, and get the optimized shape. The last step is converting the output to a printable shape and running one more simulation to double-check it is strong enough.
This particular holder is a filament spool holder designed to be loaded with up to 5.5kg of filament (1x2.5kg, 3x1kg).
Inventor has a GUI for it. There are more options.
A slightly higher wall count for prints and the weight of the unoptimized solid is pointless in this instance as it starts with a larger slab and tell it to remove x% of weight. With the simulation result you either increase or decrease the x% removed setting and run it again till the load part strength is correct. Very basic in this regard but this was a quick design. How the spool is relative to the mounting points isn’t optimized. It was just me drawing something.
This particular part is 70g each with the filament being approx. 100mm moved forward (leaver length) and were simulated to withstand roughly 12kg and tested with 5.5kg+spool weights.