RE: Prusa PEI sheet alternatives.
You want to remove the old PEI. Was able to get one off with Limonene. Smelled great, but it was a mess to work with. I've heard Goo-Gone is easier. I can't say it was worth all the effort unless you're in a stubborn tinkerer mood.
I would recommend doing this if and only if new or used build plates are no longer available anywhere in the known universe at any price!
It is not worth the hassle!
It's a royal pain in the @$$ and you are stuck with a quantity of toxic and flammable sludge that in most jurisdictions is difficult to legally dispose of.
Please see the thread I referred to above if you are even considering this!
On the other hand, I was recently able to salvage a (non-Prusa brand) PEI build plate which was scored by another user running the Live Z too low. If this happens, it's probably not necessary to replace the PEI. I was able to get it to a usable state with a sanding sponge and about 10 minutes of elbow grease.
Yesterday I printed a project box on it, and on the bottom, if you did not know that the slight 'image' is there, you would not notice it. I'm printing a catbox scoop on it now and expect nothing to be visible.
You want to remove the old PEI. Was able to get one off with Limonene. Smelled great, but it was a mess to work with. I've heard Goo-Gone is easier. I can't say it was worth all the effort unless you're in a stubborn tinkerer mood.
I respectfully disagree. To each their own. As noted above after freezing the Prusa plates the old PEI sheet popped right off, and using xylol the old adhesive was very easy to remove. As far as disposal, there is a local recycler who takes hazardous materials a few times a year so it is not hard to dispose of for me.
Ultimately this comes down to print quality and cost. For me the quality of the BuildTak PEI sheet is as good or better than the Prusa. I find that the prints somehow both stick better and release easier using the BuildTak sheets. I have 6 printers and have stripped 6 old Prusa smooth sheets and installed the BuildTak PEI sheets and I am very happy with the results. Unfortunately BuildTak has increased their costs recently so the savings aren't as high as when I first did this, but it's still considerably less expensive over the long haul for my 6 printers.