I need some guidance, probably only because I'm not googling the right words. I want to build a platform (probably some sheet of metal) which can be heated to about 50°C (or 122°F), controlled by a PID running on an Arduino. I will put trays with chemicals onto it to heat them slightly. The only idea I had so far was to use one or two cheap 220VAC heating elements (see: http://www.ebay.com/itm/AC-220V-400W-9-3-x-100mm-Cartridge-Heater-Mold-Heating-Element-/150952553177?pt=LH_DefaultDomain_0&hash=item2325792ad9
), attached under the metal sheet. The problem I face so far are the way I could attach them (as well as the thermo-sensor) that they heat efficiently.
If someone knows a way to attach the heating elements, knows a similar project (or could help me with the right words to google it), or has a solution which would work with lower voltages, I would be really happy.