I've looked, and I can't find my pics (though I know I have some, and my sump is currently for sale lol!)
Somewhere around 15 or more years ago I built a sump out of a 55 gallon tank. I modeled it after Mark Leveson's (aka
melevsreef) model F sump design. The design brings water in to each side of the sump, with the return section in the middle. I liked this back in the day because it did have a large 'fuge section, and room for my (back then) 10" Reef Octopus skimmer.
For this sump, I did my best to measure and then have a glass shop cut the glass baffles for me. That was a lot of work lol!
If I had to do it again, and I have since.....
I'd suggest a prefabbed acrylic kit for your baffles. After A LOT of research, and having owned a FijiCube kit, I now think the best value for a DIY sump baffle kit is this from eBay:
https://www.ebay.com/itm/275676397759?var=577053700520
I'm not sure if they make a kit for a 55, but I would reach out and ask. The seller was very responsive to me, and definitely makes a really nice product.
Good luck!