High Volume Dimensional Stability Issues


Hey Friends,

I’m making some large scale models that are made out of 20+ full build volume parts hollowed out, slotted and keyed together.

Unfortunately what I’m noticing is that the mating faces or flat edges where these models are supposed to come together almost always have a curve to them. Nothing some bondo and a good bit of sanding can’t fix but I’m wondering if there’s anyway to get better dimensional stability for large volume parts?

pic here: