I do keep a spreadsheet of all the materials and ancillary costs on case the tax man comes a knocking.

Even "time" on the laser and tool wear and tear. 
But you are right, no accounting for puttering, beer, and pondering.
Local market is not very affluent and I don't account for labor either, but I at least make sure to cover the direct costs. 

I have a decent day job so I'm not starving and the wife sets up at the main intersection selling oranges at the traffic light so I consider the uncompensated portions my entertainment budget. 🤠