That's great! Get the biggest sheetpan that will fit in your oven and pour he concrete onto it as thick as you can. Let it dry and boom your in business. Both ovens I've built required a slow heat up to allow all the masonry to dry out completely. You could do something similar with this...
2015 KTM 690 Enduro R, 2008 Yamaha WR250R, 1971 Lambretta DL