I haven’t tried Fimo Air yet – or I haven’t tried microwaving it – but I guess it makes sense that you could. It’s not plastic-y polymer clay that would burn badly and I’ve dried paper pulp in the microwave. This tutorial uses a simple cutout sheet, microwaved quickly to dry it, to make a luminary. Tuck your tealight or LED in it and voila, adorable lit-up hearts. As Jen, from the Mad House, says in her tutorial – it sure cuts down on drying time and impatient kiddo issues!
You could, absolutely, do this with oven bake clays. A sheet this thick probably wouldn’t even need the former to support it during baking although I probably would. With oven-bake clay, you could use translucent or translucent white fimo 
for added effect.
Looking for air-drying clay? We highly recommend Das Air dry clay, we have been using this product for over 30 years. Check out their Das White Air drying clay
and their Terracotta Air drying clay
version for a natural pottery feel. For larger crafts we recommend buying your air drying clay in bulk
This is sch a great idea – thanks for sharing!
It’s pretty darn cute and it looks fairly simple to do for those of us with impressive cutter collections.