Making bent plywood forms is an involved business, even not accounting for the steaming. Industrial practitioners have expensive hydraulic presses, whereas shops making one-offs or limited runs have to construct both male and female purpose-built forms; and the more complicated the final shape, the crazier the clamping process gets.
British company Curvomatic seeks to make bentwood creation easier with its titular product. A series of identical metal extrusions are fitting together into a sort of snakelike fence, in most cases taking the place of the topmost form. The idea behind the multi-pronged solution is to provide even pressure, simplify clamping—in some cases band clamps can be used rather than bar clamps—and save material, for applications where the Curvomatic can supplant the second, concave form.
It also allows you to create curved shapes with undercuts, which would require at least three forms to achieve using conventional methods. Check out the video to see it in action:
I don't have enough experience with creating bentwood forms (exactly zero, to be precise) to comment on the efficacy of the Curvomatic's design, but they have a customer testimony section on their website showing a variety of applications.