A frame 4" wide by 1.5+" deep is a big hunk o'lumber. It is not so easy these days to find a piece of tree this size. Plus it would be crazy heavy.
BUT, it could be assembled.
Any closed corner frame mfr. can add depth to almost any profile. call them to get a price first. It ain't cheap.
For a less expensive option, find a 4" wide moulding you like, or stack two or three together to get there. Then consider adding yet another gold (or whatever) frame cut on its back and added to the side for the depth you need. If you need an additional 1" depth, you will need to choose a moulding that is at least 1" wide.
Good luck visualizing this: I know of no good way to explain it.
Anyone know of a picture/diagram I could link to for this?
edie the paintingpictureswithwords goddess