My frames came from Betterbee. I put some together with no glue or nails and placed them in the deeps I made. Now for most people they would probably have looked OK. But I have this thing about exact parallel lines. And some of these things looked a little OFF. I went back and checked things over and found as one would when working with wood, not all things come out exactly right. Each of the side parts of the frame had a thick part and a thin part on each side of the slot where the top bar sits.
I took them all apart and compared each one to another as I put them back together, making sure to place each of the thick sides the same direction on the top bar. I also found that some of the side pieces were just a tad wider than others so I matched them also.
It looked a heck of a lot better when I got done and thought perhaps there might be others out there as picky as I am and would like to know this.