1. How do you position the rails? Can somebody link me to more info?
2. For an underfolder, are there any flats, or should I do the drilling myself? Is the inletting best done after the receiver is folded, or before?
3. Where can I find paper templates, especially ones for underfolders?

Thanks

1.      Here is a link that should be useful, the drill bit can vary from C to J.  Mostly I have heard to use an  'E' bit.
Lower Rails

2.      Use a normal flat, if you are feeling brave, try one without any trunnion holes or any in the back.  I think that Nodak sells flats without trunnion and rear tang holes predilled.  

3.       I do not know... maybe some one else can help out on this....I have the Ace Arms template in PDF, and if that would help, I would be happy to send it to you. It is 2 megs, I just need an E-mail addy.

Good luck with your build

1. on mine I installed the trunion, then lined the rails up to the ledge where the bolt rides into the trunion, clamp in place, then welded.
2. I've seen underfolder flats listed on one of the smaller dealer sites( can't remember which one ), but it was priced around $35 or $40 bucks, from my understanding, its best to use a normal formed flat or receiver, install/attach the rear tang/trunion, then drill a hole where the pin fits through, and open up with a dremel.
3. don't know about the templates, I've never seen any.

Ace Template

A short peice of 1/4" square stock from Lowes works well for me
I have the DPH jig and the 1/4" stock works just right for AMD and Romy bilds
I had better luck that way than with the "C" drill as the top rail width matters with a round spacer but not with a square one.
With Scott's excelent jig and the Tapco flats the 1/4" stcok spacer lines up lower rails with trunion and lines up the rail hole with the pin hole

The drill or 1/4" square stock or whatever you end up using is just to keep the lower rail parallel to the top rail.  I have used several different size drills.  I just keep trying different ones from my index until I find one that sets the rails so that they line up with the trunnion.  The reference to the "C" drill is just a starting point.

Mack; Thanks for the link. It is very helpful for the first time builder.

yes, thanks a lot. Those links will be very helpful. Nodak does have flats with no trunion holes! Good to know