Stretching sprue has become second nature to me, it's really easy once you get the hang of it.
Just let the plastic soften to the point where you can push each end of the sprue toward the other without any real effort, then take the plastic away from the flame and pull your arms out as far as they can go. Don't pull too fast, but rather at a moderately quick and steady pace.
Alotta folks make the mistake of leaving the sprue over or near the flame as they pull, and, of course, the heat will melt it apart almost instantly once you start to pull. Another mistake is not allowing the plastic to get soft enough which will cause it to snap.
There's a few other things that can go wrong, but when it comes down to it this is just like anything else; practice makes perfect. Just mess around a bit and stretch sprue for a few minutes. And if you get something that's pretty good but don't need to use it just then, cut it into lengths and keep it stored somehow.
As to attaching sprue, I generally plan it out depending on what's being rigged. If I'm rigging an antenna from a mast to a tail fin, I'll drill a hole in the fin and insert one end of the sprue, using superglue. I'll then put a bit of CA on the mast in the appropriate spot, pull the spue taught and place it on the spot of glue. If the sprue's thin enough it should bond almost instantly, depending on the type of CA and how much you use. I then trim the antenna by placing a blade on the point where the line attaches to the mast and pull the free end of the sprue up, and it usually separates no problem.
If you have to go from a fin to a wing surface or to the fuselage, drill two holes and insert each end as above. If it sags a bit, strike a match and blow it out. Then pass it under the sprue; the small amount of heat still being generated will tighten the sprue and the line should come taught. Sounds daunting to some, but it's super easy.
There's undoubtedly other ways to go about it, but this is what I've done for just about all my modeling years.
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