Heated build plate

Hi all
Im attempting to build a HBP based on this
[airtripper.com]
I have 2 planes A & B
Both are on a plate size of 480x380
12v 750 watt 37amp power supply
Ramps 1.4

Plane A
Wire is 10mm apart with 4 separate wites which will be 2250mm long

Plane B
Wire is 20mm apart with 3 separate wites which will be 1540mm long

I have done the maths and I get 22 Gauge (SWG) for both planes.
Could some one please check and see if I have done it right?

I plane to use alluminium for the bed but I need something to isolate the wire from the alluminium. Anyone got any idear ad to what I can use?

Would like some input on this please.
Thanks in advance, much appreciated

Old post, but here is my take on it:

For 12V power supply you could go with self adhesive copper foil. Way easier to lay down and stay flat. plus you get a better thermal contact. You can use this calculator to compute the length / width of the trace. The most common copper foil is usually 1.4 mil thick. For electrical isolation with the aluminium bed use standard kapton tape. Same tape to be used on top of copper as well.