Well, assuming 4x2 is the width x depth and it's 1 foot tall, 8 cubic feet = 59.8 gallons. If you assume 20 gallons for the first gecko 10 gallons for each additional gecko, that works out to about 5 geckos, and as the other poster said, no more than one male. I'm sure some people would house more than that in an area of that size, but I like them to have more space than the minimum. Of course you'll want to provide lots of hides so that they're not forced to be right on top of each other, but that shouldn't be difficult in an enclosure that large.
Obviously you'll want to carefully observe them at first in order to make sure you don't have any dominance issues and that everyone is getting enough to eat, etc. Best of luck with the idea.
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0.1 Albino Leopard Gecko - Tigger
0.1 Crested Gecko - Pooh-Bear