Not 100% sure where I read it first, but the idea of using a heat shield (technically a "draft" shield) really does work! Usually on my Replicator, a part that spans across the entire build platform will curl up on both ends.
However, using a 0.8mm thick heat shield (single 0.4mm shell all around), this client part came out perfectly straight. Also helped with the start and stop filament gapping that occurs with accelerated printing.
