How to Calculate Price for CAD Design work for freelancers

I have a Project, i have given CAD design service of full Product includes modeling, assembling, Drafting, BOM, FEM, for my customer also helping in building prototype, but How do i charge or calculate price, is it based on work per hour ? it took 4 hours every day and now this project is coming to an end with working product after 1 year of R&D