Reprap Qustions

I am sorry if these questions have already been answered but I ether can not find a concussive answer or nothing at all.

1. I have remade RAMPS v1.3 and a MK1 heat bed (http://www.ebay.com/itm/RepRap-MK1-Heatbed-Heated-Bed-Heat-Prusa-Mendel-/130587006465?pt=LH_DefaultDomain_0&hash=item1e67979601) I still need a power supply
1.1 What power supply do I need? An ATX power supply? Can I get a link or an explanation on; wattage, SATA or IDE, amps....
1.1.1 What connections (and how to) do I need to buy to connect to RAMPS and MK1 heat bed to power supply
1.2 For the print bed
1.2.1 The Ply board I use to hold up the heat bed how thick should it be?
1.2.2 I need to insulate under the head bed? How/what


Vid Blog (http://www.youtube.com/watch?v=SZv-Dw0Ulig&feature=channel_video_title)

How to convert an ATX power supply

PSU build

10mm ply (3/8") should be thick enough after all you need to screw the belt clamps to it. I don't insulate mine and I use MDF at 55C for PLA it's not hot enough to burn it

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Experimenting in 3D in New Zealand

I just ordered a 12V 20A Switching Power Supply off ebay that should be good enough to drive everything - for $28

[www.ebay.com]