If you're dealing with lumber at all (or even PVC), it also pays to have a good miter saw, and right now, one of DeWalt's ...

The angle of these two walls looks to be less ... Miters: Use a Shim to Cut a Back Bevel Cut a back bevel on miter joints ...

A table saw and a compound miter saw work well for the flat cutting method. Both can cut two angles at once, the bevel and the miter. With a compound miter saw, you tilt the blade for the bevel ...