Non-shrinking Putty for filling holes in plastic

[chuck]

I needed to fill in a number of limber holes on special navy�s type II Uboat model. So I filled the holes from the inside with tamiya putty, pressing the putty through the hole until it completely filled the hole, unfortunately the putty shrank as it hardened, so it left a clear recessed gap around the perimeter of each hole even after I sanded and smoothed the surface. It is difficult to apply more putty on the exterior surface without ruining nearby surface details. Is there a putty that cures quickly and does not shrink as it cured?

[reigels]

A two part putty with a chemical hardener should be more resistant to shrinking that solvent based putties.

[Mosey Dave]

This may sound a bit "iffy," but I've had good luck with hardware-store spackle. I kid you not. Goes on easily, doesn't shrink, and scrapes/sands like a champ after drying.

[wefalck]

I have never really bothered with this modelling stuff, but always used solvent-based automobile body putty. It has to be applied in thin layers, but is very good for filling small holes. Naturally, it sands very well. Tools can be cleaned easily with acetone, which can also be used to wipe-off excess putty.

I can not recommend products, because this depends on the part of the world you are in, but they are common products in DIY and similar stores.

[Krachenvogel]

I can second the recommendation for Tamiya polyester putty. I have a number of Star Trek models I did maybe 20 years ago where I used this to fill big gaps - it was good to work with at the time, and the models are still holding up well with no cracks forming in the puttied joints, even in nasty spots like the roots of the Enterprise's warp pylons.

[bigtodd]

magic sculpt epoxy. Just like the two part above. It is easy to mix and can be smoothed with water and a brush. If you need to sand it down smoother, it is like butter.
I have been using it for twenty years! That is how much I like it.

Cheers,
Todd