I know some of the wire Nik supplies has a hard insulation cover and I have found that it pays to warm it up with a hot air gun before you do the last few turns with your drill. It then seems to hold its shape better when you remove it from the chuck.

  Would be good to answer this since we get this all the time:

  There's nothing special in the wire or way we twist the heaters.

  We use regular UL1015 wire (PVC), and then clamp 1 side (use whatever, a real clamp even)and twist.

  Work patiently, you'd be able to see if the twist goes nice or not.

  Twist quite some length. You'd cut em to do each section (tube to tube). Approx roughly before cutting - cut extra, cause you'd need to solder, and then re-shape so it sits nice.
 
  I guess a video would be good for this. But key is twisting nicely, and also patience!

Thanks!

Nik
 

The short answer is "yes".  Either method will work just fine long as you keep the grid wires a reasonable distance away from  the heater wires. 

I've built some clones that didn't even twist the wires and had no hum issues.  The Soldano SLO 100 and X88R 3 channel preamp are good examples.

My SLO clone from 99'.

http://webpages.charter.net/jlemoine/preamp.jpg



Grounding layout seems to be the most important hum producer with tube quality and output bias matching also a consideration.

And as far as the OP, get your wiring in position however you can with removable tape, hot glue, tie wraps and wooden splints, whatever and after a period of time, it will "set" into that position and you can remove the sticky stuff later.  Heat speeds up the process. 

I know, I know, you want to take those pretty pictures of the insides and show it off, but after a few years, you can remove every tie, strap, or whatever in a piece of electronics and not a single wire will move.