I just recently bought a PEI flexible build plate for my CR-200B. After installing it I realized two things:

1 - After applying the magnetic layer on the heated bed I wouldn't be able to use the glass build plate anymore.

2 - I didn't quite like the textured PEI finish on the bottom of the prints. It adds an additional gap if you intend to glue parts together.

I already ordered a sheet metal build plate with a smooth finish, but in the meantime I made these clips so I could put the glass build plate back on if needed.

It's spaced to securely hold together the heated bed with the magnetic layer and the glass build plate, which altogether are 8 mm thick, without getting in the way of the printhead. Mine is modded to fit 2x 4020 blowers, so I recommend printing just one clamp first and making sure it won't get in the way of your setup.

As shown in the pictures, for the CR200-B you can't have any clamps on the left side, just front, right and back.

I've printed mine in PETG, to be used with PLA prints. Remember to use a filament that can withstand more then the heated bed temperature you'll be printing with.

UPDATE#1: If you a BL-Touch or CR-Touch take care where you place the clamps on the right side, because the hot end can get in contact with it while probing.