How to make a 6 pin pcie connector ?
You reach deep down into your wallet and pull out a rectangular piece of plastic (or paper) and say 'Yes, I'll take 2 of those' to the cashier.
Seriously. I wouldn't try 'making' anything. Molex to PCI-E power adapters and even PCI-E power splitters are cheap enough. I picked up a bunch at my local shop cause I didn't want to wait for newegg's delivery. Sure your local pc shop will have them. They were a few bucks each. Not a whole lot more then ordering them but without the wait. As mentioned as long as you have enough power coming outta your PSU, it'll be fine.
If the card itself is bad, then this naturally wouldn't do anything to help.