Second try in making own gear. My idea is to show you guys the fact that this space can be utilized. I have never seen anyone using it before so I gave it a try. Should work for those who rides asphalt mostly.

In order to make the bag I took few measurements on a frame with a ruler and drew 2 triangles and 3 rectangles on a fabric with extra 0.5 cm ( .2 inches ) on the sides for stitching it together. I did screwed up on one side and didn't stich face-to-face ( visible on 4th photo ).

As lining fabric ( it's optional ) I used some white sheets.

This bag can carry 26" tire tube with some extra space for hex keys. Bag is compatible with my previous one. Holds real tight in place.

I hope this motivates someone to try the same or even better ( since I'm still inexperienced )

Hi bikepackers   ! That's my first post here and my first DIY/MYOG attempt.

Little backstory. On my first bike travelling journey I got cheapest sleeping bag and a tent from AliExpress. Tent is pretty large so I just put it inside my drop handlebar and attached sleeping bag to the seat with paracord. It worked, yet I was lacking ability to use handlebar in a way it was designed to. Also sleeping bag got damp on a way back home.

Main problem was to put long tent poles somewhere and not handlebar. Frame was too small to attach them. So I came up with this design!

There is not much to explain. I just took a piece of fabric and wrapped it around tent poles and cut appropriated size. Then sewn it inside out. Hardest part was to turn it back inside out so I used mop stick for that  

Also, if you're going to make bag like this make sure to consider the fact that the top velcro piece should be laying on frame tube where brakes are attached ( shown on second pic ).

And yeah, sometimes it does touch my right leg while pedalling, but just slightly ( barely noticing ). Bag doesn't swing.