I have a cheap anet a6 printer I bought for the kids to play with. Then I realized if I doubled the bed length (easily done) I could actually use it for my personal projects. So my bed is 220x440mm (8.75"x18") and I need a heated bed. I have a full machine shop available so I cut an aluminum bed. But where can I get a rectangular heat element? Or how can I control 2 8x8 heat silicone heating elements?