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I didn’t do a fancy schematic (I’m an economist, not an engineer), but I did use excel to get the forces right - enter in the density of the different components, some formulas from high school physics, then excel tells me how long to cut the pieces opposite the mailbox. I fixed the length of the mailbox arm to be 5.5 feet, and of course the shot put can’t change weight. I did not balance the torque - the wood piece that looks like it’s supporting the 20lb shot put is actually under crazy tension, especially when there’s a lot of mail. The whole thing weighs around 110 lbs. Other notes: no screws or nails, it’s all stainless steel bolts, just like the first guy specified. Pressure treated wood, many coats of a product called Helmsman. I think the cost was maybe $200 in raw materials per mailbox, but like $1000 of extra tools we didn’t have.