What to use when filling large spaces? Is bondo still recommended?

[SephYuyX]

I didnt have the right tools to make good miter joints, so I just stuck to butts, but as you can see it leaves these wonderful openings.
While im not worried about this particular one circled in red, there is one on the next join up in the front that id like to fill, and then sand and paint.
But what should I use?



But what should I use?
I hear to use bondo for the countersunk holes, but what about in large applications?
Is drywall mud and wood fill really still bad for this application?
Is there any mud/fill that wont shrink/expand?

Thanks.

[Queeg]

I used bondo all purpose home repair putty for that exact application and it worked fine. it was thick enough to hold its shape when filling large voids yet malleable enough to form and smooth.

10$ for a container at home depot, plenty for a whole cabinet's worth of joints.

It also took paint well and sanded pretty easily.

[ChadTower]

Depends if you need it structural or cosmetic.  If it's structural I would probably want to stick something in there and then bondo or glue fill the remaining gaps.  If it's cosmetic, bondo will do just fine.  Why is it such a big deal inside the cab?

[SephYuyX]

It's cosmetic; the red circled one was just an example, the one I want to fill will be on the outside.

[Chadwick]

If you're just filling a joint seam, and not filling up a big void, just use 100% latex caulk (no silicone in it).  It provides elasticity so it can shrink/expand with your wood and not crack, and since it has no silicone in it, it will take paint just fine.