Would a miniature model really be a useful part of the process though?It would take nifty trigonometry to scale up the curve of the lintels to full size - when all they needed was a stick and a rope to scratch the exact required arc on the ground. If it really is a miniature megalith then maybe we're talking good old ritual rather than a practical purpose - which opens the door to a whole new world of speculation.
Portatemples for instance
;)