I've made a small frame with a 'front door' to cover an electrical fuse box. I went to great pains to get the frame flat and square.
However when I came to fix it to the (plastered/stucco) wall it turns out the wall of far from flat.
I'd welcome some suggestions on how to try to adapt my frame to fit the wall profile better (Other than a load of silicone filler)
What you're looking to do is called scribing to fit and it's a standard part of most fitting of wooden elements to uneven walls.
At minimum it can be used to get the edge to mate neatly against a wall that's a little out of plumb, next level above that would a surface that's slightly wavy and at the extreme end a very irregular or bumpy surface like a brick wall. In each case the basic marking-out technique can be very simple and straightforward, it's just the amount of work needed, and possibly the tools required, to remove the excess wood that changes.
Here are a few of the common ways to scribe an edge:
For removing the excess wood the tools needed change depending on how much and what type of shaping is required. At the simplest end just a hand plane will do (or a saw), for wavy edges a spokeshave, rasps and/or files, and for extremely irregular edges it's now common to use a jigsaw.
The basic scribing process is simple but the details of applying it to various situations can take a bit to get your head around so it's best to read through a few detailed guides so you're clear on what's involved:
How to Scribe for a Perfect Fit on The Family Handyman.
How to scribe timber for a perfect fit on Carpentry Tips and Tricks.
Learn how to scribe on The DIY World.
If your frame is made of wood you could plane the areas that keep the rest of the frame out from the wall. Or you can trim the wall.
I had this same problem installing oak trim around windows. The interior edge detail was sheetrock jambs meeting sheetrock walls with spackled beaded corners. I removed the metal corners. But, mostly due to use of green studs in construction, the trim would not lie flat against the wall. I dealt with it like so. I lightly marked (erasable) the boundary of the trim piece. Using a straight edge, I determined which areas were high. I then cut along the wall, along the edge of where the trim would fit, in the high regions. Using a Stanley Surform "rasp-plane", I carefully sanded away the high spots. I stayed away from the very edge with the Sureform, trimming it by hand with a chisel.
This worked very well for me. I suppose it depends on how much out of true your wall is. Also, in my case, the trim was about 5/8" thick so the difference in projecting out from the wall would be less noticeable than if your frame was only, say, 1/4" thick in projection. Needless to say, this is a rather permanent fix.
