With the prices of diffusers, I was wanting to try to save some money by building my own.

I plan to make and use two of them to start and then maybe expand to more as needed.
My initial pump will be a Hiblow 120LL and I will be using a 1/2" hose, Tee'd off at 100' with two 50' sections going out to the two diffusers.

I was thinking I would try to make ring type diffusers using a 3/4 inch Melnor soaking hose. I will wrap them inside of an 8" tall hoop of rabbit cage wire, make them go around once or twice and then connect back to a Tee fitting. The cage will be about 12" in diameter but I can go larger or smaller if needed.

One of my main concerns is if I will get decent enough diffusion from a fine soaker hose or will the bubbling still be too large?

I will tell you that I bought my aeration system from one of the companies that advertise on PB, and that it came with a pair of 4' ring diffusers.
I feed one diffuser set 12' down in 16' of water with a 1/4hp Thomas pump. It keeps my little .35ac puddle nicely turned.
I ran one shallow over the winter and it kept a quarter of the pond clear all winter long.

I have another question.

The check valves I was going to purchase are rated at 2psi. I would place them as close to the diffusers as I can. Again, my line will be 100' out into the lake to a tee which will then split into two 50' lines to the diffusers. My hose will be 1/2" ID.

Will the 2psi diffusers be able to function properly?

Thanks!

Soaker hose as black rough surface style produces small bubbles. My experience with using it and similar type diffusers is they create very small bubbles, but they clog too quickly and cleaning them is IMO difficult especially on the rough textured surface of the soaker hose.

I have that type diffuser in my main pond and I clean it once a year before I move it back to deep water. I use 35% H2O2 mixed at 1 part 35% to 6 parts water (about 450-500ppm), drop diffuser in bucket and 20 min later there isn't a trace of any algal growth present.

I think I am just going to buy a couple of 12" Matala rubber disks and go with them. It won't cost that much money, likely do a better job and be less of a headache to set up. Also, I won't have to worry about purchasing and figuring out how to employ separate check valves.

Can't gp wrong with Matala.

I figure they know far more about it than me. I'd rather have a higher chance of getting it right than to spend money and time making something I'm unsure of and then having to drag it out of the pond and trying to redo it, rinse and repeat, only to finally come to a conclusion that I need to buy better equipment anyways, LOL.

Don't forget and be misled. The smooth rubber membrane diffusers also should be cleaned once a year; usually for me in spring at beginning of aeration season. Cleaning the rubber membrane diffuser becomes more important if your water is clear and algae with attached mixed growths attach the to membrane surface and pores. My diffusers in clear water will in spring have a dense greenish growth on the membrane. Air Pulsing the diffuser definitely does not clean the membrane. Snipe presents an excellent method for cleaning rough surface diffusers. Our former PB member and aeration expert Ted Lea quit selling the soaker hose type diffusers due to clogging and cleaning problems.

You just made a wise decision.

Here is an old thread on aereation that might have some useful information.

https://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=454091

Another about pressure calculation that might be helpful.

https://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=354737

My Matala disks work great! They've been in there a year now, and there is not any increase in backpressure, so I'm thinking they don't need cleaning yet.
Beware buying Matalas from eBay. The sellers buy a Matala kit, take the disk out, and then sell the base only for the kit price (free shipping!), but disguise the fact in their slick ads that they took the disk out. They show the original box in the ad that shows it includes the disk, and show a picture with the disk, but state in the fine print it's the base only. I paid a normal price for what I thought was the whole kit, but then ended up needing to order the disk alone!! Buy from a reputable pond shop or Matala.

I am purchasing just the disks and will be making my own base for them.

We have two disks in the deep bowls of our pond and two black soaker hose ones in the shallows of our pond.
We run the shallow ones 24/7 in the winter and will keep our pond open all winter.