I put together a heater for my printer and thought I would share. You can find it here on Thingiverse
It uses inexpensive parts available through Banggood and Amazon. Total cost including the power adapter is about $45.
The power supply needs to be able to supply around 8 Amps of power so get a power supply that is capable of that. The wiring should use a minimum of 18 gauge wire or the current could cause heat build up and problems. Do not use any plugs unless rated for at least 8 Amps. Hard wiring is best.
The parts were printed in PLA without any supports. Parts are included to manage the wiring and the sensor. If you use the power supply I used the plug is the same as the plug for the MOai so I have include a little plate that labels the heater plug. I printed it in two colors (layer change) so that the text would stand out. Also I included a plate that can be mounted under the power switch with Heater setting information, this is optional.
Also setup some LED lights to illuminate the interior. I used one in each corner facing down and one mounted horizontal to light up the build plate only when the door is opened. That is controlled by a micro switch that is triggered when the door opens. The other lights are on a switch mounted in the interior but I am going to replace the MOAI power switch with a double pole one and use the second section to turn on the corner LEDs when the printer is powered on. You can find it here on Thingiverse