Let's see if you can use hot glue to plug holes in steel tubing (temporary). Trying to figure out a way to fill the tube with lye for awhile to dissolve remnant aluminum seatpost. Hot glue can be chipped out easily later.
#BikeRepair #BikeTooterSurvey says.... not water tight, but it's only a slow drip.
#BikeRepair #StuckSeatPostQuestSo, I think the next thing here will be putting the entire bike in a large plastic bin (to contain any wayward drain cleaner). Plan for disposal of said drain cleaner will be the drain (municipal sewage), eventually, or massive dilution with water in the yard (not preferable).