Doreen -- there was a fairly long discussion with pictures on building a replacement bridge and downholder for a de Meglio here. The bridge design of the de Meglio is virtually identical to the Ceccherinis, so the closeups of the bridges for my Ceccherinis in the above-linked thread should give you and your luthier a reasonable idea. I recommend to use a 2mm solid brass rod (made for example by K&S and available from model-building shops) as the saddle, filed flat on one side.
The dimensions of the Ceccherini bridge are:
Length overall: 123mm
Length of saddle insert: 48mm
Overall height: 8.2mm (NB: this is the height of the bridge, but with this design,
the height of the saddle above the soundboard is less than that).
Width at base: 6.8mm
Distance from underside of saddle insert to base: 3.3mm (NB: This is the parameter that determines the height of the action and you will need to optimise it individually for your mandolin).