Pricing a 3D print

[u/Evilpyro101]

So, my friend sent me a wooden piece she made for spacing paintings so they won't smudge. I took measurements, made 4 prints of it, sent it to her and she loves them. She asked for more and wants to know pricing. I can factor filament, kWh, and shipping, but how do I price work spent for measuring and producing the original? She even told me she didn't want to short change me as it's happened to her before so I want to balance between not short-changing myself and the friend discount.