Heating up the bed or cooling it down colder in combination with something to create tension across it are your best bets. I use the chisel pry method but I’m not using the same surface as you so I don’t know how well it will work. I routinely remove large flat pieces (7" x 9") with the method with no need to make corrections to the bed level before the next print. Here is a video clip of what I’m talking about.
Go to 16:24 for part removal demonstration.
Ok so I finally got the part off. I made the bed cold with ice packs and bought a different razor that came with a handle. I slowly worked my way around the part but as it came up, it ripped a chunk out of the surface… So the part’s off and looks great but the surface on my bed is ruined… Guess I’ll go back to glass. I liked how it worked on my old printer anyway.
@Kevin_Danger_Powers Seriously – it’s all about how close your first layer is. Try with what remains of your surface: print something smallish with a brim and set the height so you can see the distinct rings of the brim and it’ll come off much too easily afterwards or perhaps mid print. Print something so there is absolutely no way of seeing the individual perimeters in the brim and the inside edge of the brim curls up slightly as it’s printing (i.e. the head is dangerously close to the bed) and it’ll be stuck too well. In between is the sweet spot.
@Mark_Wheadon I guess I’m just use to using glass. When it cools, my parts always just popped off (or required little force). This new material is just different I guess. Oh well, it’s junk now I guess. I’ll probably just get another sheet of glass. It seemed to be the easiest to use. Unless you have some other kind of magic material I haven’t heard of…
I use a PEI sheet stuck to glass on my Kossel, and my Prusa i3 MK2S has the same surface (PEI). The same thing about initial layer height matters with PEI as well though. My Prusa bed currently has a small part of the PEI missing after I pressed the first layer of an abs print too close to the bed.
I have actually ripped a section of my glass plate off with a print that was too tight. So, just changing bed material isn’t always the answer.
Heh yes I’ve done that before. I ended up with little droplet shaped pieces of glass stuck to the bottom of the print.
I’ve become a big fan of Magigoo on glass for heated bed applications.
Parts pop right off when cooled, even PETG, without “biting” out chunks of the glass bed.
I’ve ordered the removable flexable bed that Prusa is using with the MK3. Stainless steel with PEI.
I stopped using the usual spreader, as those things are bloody dangerous. They require too much force. When the print breaks free, the edge of the tool could very easily cause injury.
Turned out I had a set of chisels that work very for removing prints. As the edge of the chisel is very sharp, much less force is needed. Just rest the flat of the chisel against the bed (so the edge cannot dig into the bed), and slide the edge toward the print. Safer and more effective.
@Preston_Bannister Not to play down your advice (which sounds sensible) but the spreader moving suddenly is only dangerous if you put part of yourself in the way. I typically have both hands on the same side of the part and maybe a finger on the top of the part is small and may be lost when it pings off. As with any sharp tool always ask yourself where it would go should something give way or slip and make sure no part of you is near that trajectory. (Why do I feel like I’m tempting fate writing this. I’ll get absolutely no sympathy now if I hurt myself 
@Preston_Bannister and @Mark_Wheadon concerning using chisels (which I use) or anything really sharp for that matter (including a spreader) is the reason I use it as a pry bar. Bevel side down. The chisel does not slip and the parts pop off the bed. No damage to the bed, the part, and especially me.
A flat scraper is handy to slip under the part and keep a section raised up so I can work my way around the part with the chisel if the print is near full bed area and flat across the entire surface.
@Jeff_Parish Hmm I hadn’t thought of doing that. 
Food for thought.
@Mark_Wheadon Check out the video link in my first reply on this thread to see a chisel pry in action. It has been many months since I’ve had to re-level or replace tape.
