On 19 Mar 2018, TimR wrote in alt.home.repair:

Short piece of tape to hold it in place, then cover both sides
with the fiberglas cloth from an autobody repair kit. These come
with fiberglas reinforcement and the binder (either polyester or
epoxy depending on how cheap you are). The repair is pretty sure
to be stronger than the original.

I went to the auto part store yesterday to look for that stuff. They
had the fiberglas mesh but were out of the resin. It it's warm enough
tomorrow (I have to work outdoors) I may duct-tape it together until I
gather the materials for the final repair.