I use the lightweight vinyl spackling compound I get at Wal-Mart.  Cheap, easy to use, and it works for me.  When I use it for fillets, I wait till it has dried thoroughly (usually overnight) and then put thin CA on it.  The spackling absorbs the CA and makes it quite hard.

HTH,
Henry

I hesitate to admit it, but I use plain ol' carpenter's wood filler in a tube.  And I'll let you in on a little secret, Frank Carlisle does too!  I put it on straight from the tube, and smooth it with water on my finger. Sands nicely, takes paint very well...I don't know any down sides to it.  But then maybe I'm just not too particular.

--Ray

Hello,

Can anyone fill me in on a source for Superfil?  Sounds like pretty good stuff.

Thanks,

Joe

Hi Bill,

Thanks for the info on locating Superfil.  I'll give it a try.

Hope things are better your way.

Joe

hope im not butting in but this has been a subject of frustration with me for the last 15years or so and the cause of 3 nice scale projects to sit unfinished--and for me to almost give up on painting and just use monokote--a real turn off for nicer things.
i have been looking for something to replace the best suff i ever used- a product called softglass but cant find now and no one aroudnd here remembers it.think it was made by coverite.(most fliers around here didnt mind woodgrain paint jobs)
it looked like grey auto primer-smelled like polyester resin and used polyester hardner/mekporoxide(fiberglass resin hardner)and had short fine hairs of glass in it.(couldnt see hairs)
verry light after sanding(may have also had micro ballons in it?)
one coat--sanded mind blowing quick and 2or 3 coats of paint-1or2 coat with dark colors and looks like painted metal.
the first airplane i did with it was an r/c scale pt 19 23yrs ago and as of now it still looks like painted metal.(still fly this one)
sure wish i could find formula or current mfg.
this was super good easy to use stuff.
   any clues?
         
super fill sounds good--is it liqued or putty like epoxylite?

                David