Ya don't need any thinner.

A hair dryer on high or a heat gun on medium will thin that epoxy to a water like consistency without any thinning. Just work fast because the heat helps it set up quicker. 5 minute takes about 1 minute and 15 min speeds up to about 3 minutes. One hour stuff only slows down to about 50 minutes unless you keep the heat on it for quite a while.

And welcome back to building......