How to factor in shop expendables on an invoice?
Does anyone have any good tips on how to factor in a price for shop expendables on an invoice? I made an appliance for my friend's film - it was a silicone piece covering the actor's face to give them a really disfigured look. I'm making the invoice, and for some of my large material expenses, like the alginate and plaster for the lifecast, the ultracal, mold release, and chip brushes for the stone mold, and the Dragon Skin FX Pro silicone for the cast, I have receipts to include, because I bought these materials specifically for the project. But there's a long list of other things that I keep in my shop and used, but I don't have receipts necessarily to show what they cost, and even then I wouldn't know exactly how much I used:
- crystal clear
- alcohol and dawn
- silc pigs (Smooth-On pigments for silicone paint)
- psycho paint (Smooth-On silicone paint base)
- brush cleaner
- telesis 8
- telesis 8 thinner
- prosaide cream
- q tips
- artex (3rd degree makeup)
- skin illustrator liquids (for painting the appliance - I pre-painted 8 appliances and applied the makeup 5 times
- 99% alcohol
- alcohol palettes
- telesis 8 remover
- makeup wipes
- prosaide remover
- moisturizing lotion
One thought I just had was to count up the number of items (22) and multiply by a dollar amount. Or I could look at the cost of everything I bought specifically for the project (right now it's $171.55) and do some percentage of this. Or I could just set a flat rate for the project ($35??) Or I could charge per day? I worked 4 days preparing the stuff and 4 shooting days. Maybe $20 per shop day and $15 per shooting day?
Does anybody have a good rule of thumb? Thoughts?