I just used 1 layer of batting and cotton fabric on top, mine has been going strong for several years

This is what I did. You could even make two of them. Then you have a clean one to change to when you have to take the board somewhere and had forgoten to wash it.

My removable cover is fitted at one end and elasticized at the other end. I have also put some markings on it with a perma pen. It's handy to have inch markings from one end to the other. Not for accurate measurements but for knowing if you have enough or almost enough of what you are pressing.

I have also put an outline of a 12/5 in square. This helped me keep a bias edged square "honest" a few years ago, and I have used it since a few times.

Several years ago, DH and I made our version of the Big Board for a fraction of the cost. I used two layers of cotton batting (it's still there, and I use quilting fabric (what was I thinking type) as the outside cover. I replace it periodically when it gets yucky.

My board is 24" x 48" with skids on the bottom so I can lift it easily. I have made both and the silver fabric gave out after a couple years. Mine is plywood, insulbrite, cotton batting and cotton duck with two removable muslin covers for the board so when I starch I can wash one and have one ready. I sewed a casing around all four sides and used cotton yarn for gathering and tied it in on the sides. Mattress straps secure it across the board underneath to make them tight. The clips on the mattress straps are like the old fashioned garter belt clips with one at each end and elastic in between. My cutting board sits on top when in use.

I pretty much did the same thing as everyone else, however the first go around I used two layers of Warm and Natural and I found that to be too squishy. So I removed one layer and just had the silver stuff, Warm and Natural and a layer of thick Denim (which doesn't show the stains as much). Now I just love it.

By the way, what is scrim?

The idea of using a wool blanket is a great idea. You may want to shrink it before you use it, however, if it is an old blanket.

By the way, if you don't have insulbrite (the silver stuff) you can use a layer of heavy duty aluminum foil instead. Works just as well. In fact, I made a small ironing board to take to class over 20 years ago and it is still working well.

I guess I was just cheaper than the rest of you. Had an old mattress pad that I cut in half and stapled to my board. I cover that with muslin that I can take off and wash when it gets too nasty. have been using this for years and the muslin is getting thin in places. we marked the sides of the ironing board on the bottom of the plywood and screwed
stops in a few places around it, now it is easy to put in place and have it stay put until I want to remove it

I saw a pressing station, perhaps on this board, that was made out of a baby changing table. So the next baby changing table I saw I bought. It took me 3 years and moving it twice to get it done but now it is. An Amish woman came in and saw it and exclaimed..What are YOU doing with a baby changing table? I'm 70 years old. I had to explain it was an ironing station. The three drawers and filled with pre-cuts, and the tall cupboard has my larger accuquilt dies.

I read somewhere that if your pressing service is too padded, you can distort your blocks when you press them.