Before starting to physically work on the leavening cell, I designed everything on the computer with the google sketchup software, so I limited the errors and construction costs.
The structure is made with 20x20 aluminum profiles that are normally used to make 3D frames, CNC, etc. TThe profiles are held together with aluminum angulars for 20x20 profiles. In the inner wall of the cell and in the upper part, I fixed a metal grid (it can be of any material as long as it has a certain rigidity and can withstand at least up to 40-50 ° C). As a heating element I used a heated 50 watt cable, 6 meters long normally used to heat aquariums and terrariums. The heated cable is fixed to the metal grid by means of plastic clamps.
For the covering of the aluminum frame I used 6 mm thick wooden panels, the inner walls were covered with heat-reflecting insulating material (or the common aluminum roll fixed with double-sided adhesive tape). For the temperature control of the leavening cell I used a double timer with relay output and a thermostat with probe. Internally, at the top I inserted a 12VDC LED lamp. On the front panel, in addition to a double timer and a thermostat, there is also a general on / off switch, an on / off button for the lamp. At the top, hidden from view, I inserted a low voltage power supply (12 VDC) and the relative wiring. On the back there is a general 220VAC power outlet with an illuminated switch and a fuse.