I fully understand the bride hole problem. Thats probally the hardest thing to get right from scratch the first time. EVERY wire on a hd runs across a bridge and through the holes at a different angle. There is no exact duplicates either.
You have to think in 3 dimensions all at once and that's not easy at all.
I cheated with my scratch built ones by using auto cad inventor a 3d solid modeling drafting program that can build up some really complex stuff like a compete F 16. All I had to do was create the parts and fit them together then rotate things around where I could look essentially down the center of the strings like they were tubes. After I cranked in the data that defines the physical properties of the woods I used like the force needed to break the wood I had all I needed to run some stress checking on it I knew exactly what was going to happen to the HD stress wise long before I even got any wood. Then all I did was print out the prints for the parts and cut them to the exact dimensions there. No wasted wood from guessing at things or mis fitting parts at all. Those prints could be accurate down to about .0001 of an inch but I set the the limit at a 64th of an inch when i did the prints. One of the guys in the machine shop made one from the CNC control code generated from that program too. CNC mills are neat to watch while chewing out parts.
At the time I had the complete resources of the entire engineering, physics and music departments of a fairly large private college at my disposal while working there. Well over a couple million worth of lab stuff available to run tests with too like an environmental chamber where you can control things like temperature, air pressure, and humidity at nearly what NASA is capable of doing. Its was interesting seeing the effects on what the average conditions at 40 thousand feet has on a HD verses at ground level. I am retired now but I still have some limited access to the same things.
The only thing I couldn't test out was the amount of tuning change at normal earth gravity to what it would be at say on the moon. There was no way to create artificial gravity to do it. If you check out the string tension formula part of it is based on the acceleration of earth gravity that is actually 32 feet per second. On the moon gravity its far less so the tuning would shift all else being equal. Its easy to come up with the values by changing that value in the formula but its neater to actually see and hear it.
That is why I know exactly how a HD acts under the stresses. All it takes is to guess a bit from the values on mine to others. There is a limit to how far simulations can get such as there is no way to predict the exact sound you will get out of an instrument but you can get amazingly close but that involves some really serious math best done on a computer with the right software instead of just a calculator. Things like a bit thicker coat of finish does have its effects..