I finally evicted the assortment of too-small and too-holey t-shirts that have been living in my dresser. I hoped to make them useful as grocery bags. Three cuts and three seams per shirt was all it took. As a bonus, I get to sentimentally hang on to my college t-shirts a bit longer.
Here are the instructions I followed.
Today I used my new bags to get the groceries home, and they performed admirably.