Quick release clips for a Carrdice Barley bag, and an internal stiffener made from a campaign sign:



The interior wooden rod was replaced with a metal rod, and attach to the bag with fender drawbolts:





With a handy strap to carry it when off the bike:


And the stand-off to hold it away from legs, made from a Klickfix seat bag support. [MENTION=114373]northbend[/MENTION], who now owns this bag (none of my current saddles can use it), has improved the stand-off retention method using a leather strap instead of zip ties: