I've been having lots of corydoras eggs fungus lately, and I don't know why. For the latest batch, gold and green lasers last weekend, I took all the fish out of a 10 gallon, added a bunch of java moss and 10-15 drops of Methylene Blue, set the moss in the flow from the spray bar, and dropped the eggs in the moss.
Won't know if it it worked until I see wrigglers.
I don't know whether a tumbler will work for cory eggs. I agree with Christine that it's probably best to mimic natural conditions. In my experience, most, but not all, corydoras tend to put their eggs in high flow areas, so it's probably good to have a good flow wherever you put them. A tumbler does that, of course, but it's not natural for cory eggs to move much.
Our speaker last April, who was a fantastic corydoras breeder, recommended leaving the eggs in place and removing the other fish. I did that recently, but the eggs fungused anyway. I didn't add Methylene Blue, and now wish I had. Sam reports that Arthur did not have much, if any, problem with eggs fungusing.