Source: Acrylic Sheet for Print Surface
acrylic sheets as my 3D print surface. I have tried many other types: glass, ABS slurry on Kapton, blue painter’s tape, and Kapton on aluminum (described at the end of this previous post). This surface works the best BY FAR. I use a thin sheet of acrylic on top of an eighth inch precision aluminum plate over the heated bed. The RepRap bed is not very rigid, and the acrylic is even more flexible. The aluminum sheet passes the heat from the bed to the acrylic and also provides complete rigidity. When the print is done, the acrylic can be flexed to pop off the model.
If you are prying your 3D prints off of a bed using a chisel, STOP. You will usually wreck your model and might hurt yourself.