The barrel on the 10-inch I had a few years ago, as well as lots of others out there, looked like it was made from the insert of a super-sized roll of toilet paper.
Another key factor is a very lightweight mirror (a thickness to diameter ratio of 2 or even 1.5 vs 6 for a “standard” mirror), plus the extensive use of recycled or repurposed materials. Lots of 12” Dobs were made with a salvaged porthole glass.
The barrel on the 10-inch I had a few years ago, as well as lots of others out there, looked like it was made from the insert of a super-sized roll of toilet paper.