This is the one I use.I think by heat treating one limb at a time ,it give more control of the process ,because it counter balances any imperfections that the form may have.Also with that style you have to be very careful not to cook the back because the vertical board has a tendancy to direct heat to the inside. At the right angle.I make mind by bending an aluminum yard stick to a cuvre I like ,hold in place with nail ,trace and cut out.my first caul was like yours,just saying what has worked best for me so far ! Good luck!