Once in a while you can find thicker sheet goods at Farm and Fleet. They are used in hog confinements. But it's not PVC and it's very heavy.
If you're just lining cage floors, you should be able to find thin Sintra or another brand of expanded PVC at just about any plastic distributor if you live in or near a larger city. If not, then check with local sign shops.
For cage floors I also like scrap linoleum or other vinyl flooring. Wall paneling rated for showers also works well.
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Current snakes:
0.0.1 Gonyosoma oxycephala - Java locale (green)
1.2 Gonyosoma oxycephala - Jave local (green)
2.2 Gonyosoma janseni - Seleyar locale (all black)
1.2 Gonyosoma janseni - Celebes locale (Black & Tan)