We had a thread like this awhile back. (Although this ain't Off Topic, I stuck it here anyway. Mike/Dean/Jack--feel free to move the thread and delete this parenthesis text if you deem fit.)
There seems to be a nice group of new builders getting started all at once, and I thought it would be helpful to once again own up to our stupidest building mistakes--so they don't make those SAME mistakes.
I'll start:
When I was cutting my exterior skins, and I matched up one side that was already cut to now cut the other, I didn't face them properly, so the finished "nice" side was on the wrong side. Making that piece of expensive birch totally useless.
I fixed my boo boo by deciding to skin my interior with the same stuff, so I was able to use the piece for that.