Some people swear by gluing paper to balsa, but for a small, delicate
model like the OT this is going to be (1) difficult, (2) heavy, and (3) probably
won't look that good.
Dope sanding sealer is still widely used. You can also experiment with
tissuing. Dope the balsa, then sand smooth, to remove fuzzies and dirt.
Then apply sheets of model airplane tissue, adhering with thinned dope.
Apply one or two more light coats of thinned dope to fill the weave of the
tissue, drying thoroughly and smoothing with very fine sandpaper between
On a model as complex as the OT though, tissuing will require lots of
time and patience. My personal recommendation would be to just use
Oh almost forgot... another product worth trying is Elmer's Fill N Finish,
it's a spackle-like product for filling holes in wood. Many people swear by
thinned FNF (it's water based). I think for smaller models, dope sanding
sealer is better though.