Seeds and stringy pulp from around nine pumpkins.
I tried an outside method of cleaning and separating over a screen with the hose, but the holes in the screen were too big and the seeds kept falling through. So I did the washing inside in the sink.
Lesson: don't wait any number of days before separating pulp from pumpkin seeds. Do it as soon as the stuff is taken out of the pumpkins. The strings will cling too much to the seeds otherwise. I had to do numerous washings.
After washing I got some window screen and put the seeds on it to dry with a fan at medium speed and oscillating at enough of a distance to move the air around but not blast the seeds with air.
They should dry for up to three weeks. Even if they look and feel quite dry, one should leave them for the three weeks.
Of course not all of them are viable. Some are empty, which can be told by the flatness of the seed and the give when you press it between your fingers. Do not use the floating test for squash seeds (where you put the seeds in water to see which ones float and which ones sink; the sinkers being the viable seeds and the floaters being duds), as viable squash seeds can both sink and float. This may hold true for other seeds as well. The float test should be used only for those kinds of seeds which for a certainty only sink when viable.