I am anxiously prepping to eventually do the Tour Divide. (Working on carrying over sufficient vacation days and $aving up for a gravel bike.)
In the spirit of being self-supported, I will be designing/making my own frame bag. Fortunately I have access to a sewing machine and my wife who knows how to use it...so it will be a team-effort. We looked at several bags in REI. She saw the frame bags and said, yeah, that should be simple enough, but when she reviewed the seat bag, she said - better just buy this one. We made 3 bags (top tube, frame, and gerry-can) for when I did the Colorado Trail Race in 2018 for my full suspension bike that worked great and saved $$$. Looking forward to doing it again for Tour Divide setup.