Add an heated bed to your microcube, to improve bed tickness for PLA, and allow it to print PETG, and more (maybe ABS if your heater patch is powerfull enough to reach 110°C).

Beware: An heating bed require a lot a power. You MUST ensure your power supply is strong enough. The printer alone need at least 60W (says 70W for safety). You power supply must be 70W PLUS the Watt power of the heating patch you will be using (plus another safety margin, to be sure). I'm using a 120W power supply for a 40W heating patch.
It's even more important if you are using a cheap chinese power supply (which are usually goods, but often lacks of security cutoff for that price).

I'll need:

• An aluminium plate, 150x150mm, 1.5-2mm tickness (less, and it may bend, resulting with an unplane bed ; more tick will work but impact the heating speed). Cost me about 4€
• A 12V heating film that fit your aluminum plate.
  • I'm using this one (100mm, circle, 40W), but search "polyimide heater" on ebay & his friends.
  • Silicon heater patch are also good choices (but a bit more expansive).
  • The Watt value of the patch has a direct impact on the heating speed and and maximum temperature. The higher, the better, but you MUST ensure your power supply can drive it. And too high power are useless for that printer size (I think above 50/60W is useless ; below 20/25W will be hard to use).
• A standard 100k NTC thermistor
• Kapton/polyimide adhesive for fixing thermistor and insulation material
• Optional: a 150x150mm glass or mirror for a better adhesion and plane.
• Optional: insulation material and/or cork sheet

**Instuctions:"

• Drill 4 M3/4 holes at the corner of your aluminium plate, the center at 5mm for each side (like you should have done for your actual bed plate)
• If you intend to use a glass/mirror, countersink the holes on the top of the plate to use contersunk screws
• Fix the heating patch on the bottom of the aluminuim plate, on the center. Ensure sur wire are on the same side of the RAMPS of the microcube
• Put the thermistor on the center of the patch, and fix it with a large piece of Kapton. The wire on the same direction as the heated patch wires.
• Fix the wires to the plate with Kapton
• If you use insulating matertial, cut them at the aluminium plate size, and fix them using Kapton. Cotton/heat resistante material first, cork last.
• Add screw and spring on each corner, fix your bed on the Microcube plateform
• Connect the patch wire to the RAMPS heated bed output (D8, the one near the main power in).
• Connect the thermistor wire into the appropriate ntc sensor (the one juste next to the hotend thermistor).
• Configure your firmware to enable heated bed. This bed can easly support a 120°C max temperature (if your patch can reach this temperature).

Insulation:

It's not necessary, but it will improve the heating speed and the max temperature.

For information, this is what I measure with my setup (2mm tickness aluminium plate, 40W 100mm diameter polyimide heating patch) :

Without insulation:

• ambiant (25°C) to 60°C in 4 minutes
• max temperature: 80°C

With insulation (2mm insulating cotton + 2mm cork):

• ambiant (25°C) to 60°C in 3 minutes
• max temperature: 95°C