Have a Flashforge Creator, or equivalent model? Want to put a glass plate (great for printing PLA, and nice if you want to be able to swap in and out build plates easily, for example if you have plates of differing materials, surfaces, surface textures or surface coatings) in your printer? Use this adapter on the rear board that hits the Z endstop. this "tricks" the printer into "thinking" the built plate is actually a quarter inch higher than it is, allowing you to then put a quarter inch thick piece of glass on top of the existing build plate.

I attached my new build plate with large binder clips, and i have several plates, one with kapton for printing ABS, one blank clean glass for PLA, and several others that i can use for experimental surfaces, like the ABS slurry on glass or sanded glass. Swapping out the plates is as easy as removing the binder clips, and releveling the build plate if necessary. The glass plates are an added bonus in that if you are experiencing warping with the stock aluminum plate, the glass will be guaranteed to be planar.
You will need: quarter inch glass plate(s), of similar dimensions as your build plate, 2 (or more) large binder clips, and this adapter.
When you first set this up, tighten the screws on the bottom of the build plate as far as you can, install the adapter on the rear board of the printer (see image). Run the plate up as far as the printer allows you to check that it stops a quarter inch or more above the existing plate. You do not have to do this, but you do run the risk of ramming the plate into the nozzle if there was something wrong, like the spacer adapter not being in the correct spot, or not being printed at the right size. If there is more than a quarter inch of clearance between the nozzle and the stock build plate, then you're okay to install the quarter inch glass plate with the binder clips. I only used 2 binder clips, located in the rear left and front right of the board, as these locations are rarely seen by the nozzle (compared to the front left, where the default blob is places when starting, for example). Once everything is installed, level the build plate. When you change the plate in the future, it is advised to re-level it each time, although it shouldn't be as far off as the first time. When printing with the glass plate, you may also want to increase the bed temperature a bit, as the glass does not conduct heat as well as metal.