Generally I don’t change per hour but by commission based on fair market value based on the requirements to fill the quote.
If it’s something simple that takes 100 hours to make and the fair market price of a like product is $50 then the commission would be $50 dollars. This is assuming that I would still own the works as intellectual property and free to sell to any other market as I see fit.
If the commission is based on work for hire where the client would own the IP in full then things gets a lot more expensive as a one off and as custom work would require a contract (aka work order) outlining the details and the same 100 hours could be as high as $10,000 dollars.
A reason to go freelance is to profit from your own work and make 100% (mostly) of the full retail value that you don’t get as work for hire.