No photos this time but I did want to share what I've learned about making my own cradled hardboards:
Buy them already prepared if you can!
However, if you have to make your own because of size or if you just want to make them, then I recommend the following:
1. If you already have the artwork which you want to use on a cradled hardboard, measure it carefully then cut your hardboard 1/8 to 1/4 inches smaller than your art.
I don't care how carefully you measure, there will be mistakes. Making sure the art is slightly larger than the cradled hardboard will help with making sure the hardboard is covered when you go to glue it down. It's much easier to trim a little from art that's too large for the board than trying to make too-small art fit on your board.
If you're like me and just dive into doing something without considering all the ramifications, you may also be like me and find that your art is slightly smaller than the cradled hardboard. If that's the case, I saw a tip from an established artist (but can't remember who it was!!!) to paint the cradle and hardboard one color then trim your painting so that it will allow about 1/4 to 1/2 inch of the painted hardboard to show all around. It will kind of look like an intentional border. That's what I'm going to have to do with at least one of my two paintings!
Of course, it would have been better if I'd had to trim a tiny bit of the painting after gluing to the hardboard but --------.
2. Make the boards for your cradle just a tad smaller than each of the measurements. If you plan to cradle an 8 x 10 inch piece of art on paper, for instance, mark two pieces at 8 inches and two at 10 inches but cut on the side of the markings so you'll have slightly smaller boards than if you'd cut them on the other side of the line or even right on the line. I say this because it's much easier to fill small cracks with wood filler than to try to shave down a too-large frame board.
Since we were using hand tools, it was almost impossible to get accurate cuts for the mitered ends and I ended up trying to reduce the size of the cradle boards while still keeping the correct angle of the miter. It was a real pain and very time-consuming, but I was able to get the miters to fit in with each other although I still had to use wood filler. It would have been much simpler to have had the ends (very) slightly shorter.
3. Instead of putting the cradle/frame together before gluing to the hardboard, I recommend gluing each piece of the cradle to the hardboard so that the edges match up. If you didn't want to miter each corner, I would think that boards butted together would be just as effective if not as esthetically pleasing. I think I would do that if I ever make another one of these cradled boards.
I hope these tips help and that you'll have an easier time of building a cradled hardboard than I did. Of course, no matter what you use for your board, be sure to seal it thoroughly to keep any wood acids from leaching into your painting. And don't forget to varnish your painting after adhering it to the cradled board.
Good luck if you try this. It really shouldn't be too bad and now that I know what to expect, I think the next one I build will be much easier and quicker!