Yes yes, Prickly Gorse does not actually have a 2.5+15L pattern available, I made this bag up as I went, with a few pictures taken but honestly very few notes.
Back when I was starting my MYOG journey, I printed, taped and laminated the large fanny patch and Summit pack patterns, so while I was proceeding with this project pretty aimlessly, when I cut pattern pieces, I was starting with the MYOG Tutorial pattern pieces as starting points.
for the point where they connect, I just took the summit pack front panel, overlayed the fannypack panel, and added two seam allowances so that I could sew them together.
about the pack:
Fanny pack works about how the MYOG Tutorials version does. Same front pocket, with an added pass through zipper that I can "lock" with a mittenhook if I really need, and an attachment point for cinch straps from the wings.
main body is likewise pretty stitch for stitch from the original pattern, orange ripstop inners for visibility with some stretch pockets and another pass through zipper going back into the body of the bag.
Bottom of the fannypack has OG venom stretch mesh as a trash pocket which also conceals the webbing ladder used to attach the optional shock cord third strap. Waterbottle sleeve attaches to the bottom with lil olive toggles through cord loops
Wings are entirely freehand and original, which is why they're merely okay. Incredibly comfortable and work perfectly when worn as a fannypack/hip belt, they load a little strangely when worn as a shoulder sling, which I do most of the time. The cinch strap and venom stretch hold the pack to a fairly slim profile when the main pocket isn't filled, but can easily be expanded to hold things like a 1L nalgene.
back panel is 3d spacer mesh, wrong side out, with orange liner+quilting (is that the term?)
The +15L summit pack is kept intentionally minimalist, it's got a DCF panel where it meets the fannypack, for some minimal structure, but is just a big single zip bag, 210d gridstop back, 1.8oz airwave front. (That's right, more than a hammock fabric)
The fannypack has no structure added, the binding front and back of the backpack to the fannypack panels adds a ton of structural stiffness, and the bag itself pads the back when tucked away.
Fabric mounted buckles on either side will instead meet the top of the pack when opened, but can easily be switched around to switch which shoulder the bag sits on.
Backpack portion has a CSM poly + pallet banding horizontal stiffener which is replaceable/removable, but makes the bag look a lot better when opened.
Full 420° circumferential zipper opens the bag section, was neat figuring out how to sew it.
Bag isn't bright and shiny in these photos because most of them are after 4 months of daily use + international travel.
As always, shout out to the MYOG discord server. It's tons of fun and now pretty active. https://discord.gg/CruyFfVRVZ