Cut Edges of MDF

[Cgav34]

Any tried and true methods for smoothing the edges of MDF that have been cut?

I've been doing a few of those fancy, letter cut outs folks like to hang on their doors, but have never been happy with the edges of the MDF.

I've read where joint compound can be applied, then sanded for a smooth edge, then painted....but then I also read where this is a bad method.

Any tips??

[Sliverfoot]

I've never done what you are doing but I wonder if automotive spot putty would work better than joint compound because it would be less porous.
Just a thought.