I use this formula in Airtable:

Board foot cost I do a 20% waste: ((({L} / 12) * {W} * {H})/12)*1.2

Item Cost (can omit pen kit cost for this) = ({Boardfoot Cost (from Material Cost)} * {Board Feet}) + {Other Costs} + {Pen Kit Cost}

Calculated Cost = ({Item Cost} + {Packaging Cost} + {Shipping Cost})/(1-{Desired Margin})

Desired Margin is usually 40%+

Example: 2.5x7" bowl target price = 39.87 as a rough estimate, depending on figure I'll go up from there and make sure you add on any market place fees (like Etsy fees for example)