Ive heard about it but never done it. How do you use superglue (and what type) as a seam filler?

thanks,

Hello, Kent.
What I use is a generic gap filling super glue put out by Bob Smith Industries. I find it in my local hobby shop. I save yogurt cups and lids and use the lids to hold a couple of drops of the super glue and a toothpick to transfer the glue to the part. If the parts don't quite fit, the super glue fills any gaps. After the glue sets up, do any sanding required. Of course, always dry fit first and get the best fit you can before gluing any parts.
HTH

Is gap filling super glue different from the kind i use to glue my models together with?

Kent,
Yes. Somewhere on the container it should say "gap filling". It is thicker than the regular super glue. The kind I use is made by Bob Morris Industries "Insta-Cure" brand. Another brand is "Zap A Gap"

If the seams are not toot deep I use standard cyano and once in place i put talc powder on ite. It dries almost immediately and is easier to sand than filling superglue...
Ciao

Zap-A-Gap is what I use. I have had pretty good success with it. For larger gaps I sometimes use 5-minute epoxy.