Hi Lindsay
Just to give you a idea using cad what the insert would possibly look like without 3D engraving.
The black represents full depth cut of 5.5mm
The cyan would be cut about 2 mm deep first in a circular pattern to get all the inside of the insert down to the same depth.
The dark blue is the "V" cutter at the point going a further 1.5mm beyond the cyan depth meaning that there would be 2mm of meat left between the deepest cut and the top surface.
Note: because I can not do a tapered V cut there will be triangles (cyan) remaining at the 2mm depth mark which travel 2/3's to the centre until the point where they intersect the next high spot of the V cut. I am predicting that the green line will be a taper high spot to the centre due to the v cuts intersecting. In addition the outer inside diameter will look different to the graphic as the dark blue will be 1.5mm less inwards towards the centre.
I am guessing that when the pinball insert companies made there mould they would have machine in reverse getting tight lines to the outer diameters etc, so to machine in reverse will impossible to achieve and like your current insert.
Therefore if I was to go ahead with this, it won't be like the original and will take probably 1hr for the first one to get it close to this based that my cutters can do it. In addition the texture underneath where 2mm depth reduction machining has been performed there will be slightly circular patterns, which probably could be lightly flamed to clean up / improved - though this would be experimental as I have never done this before.
Option 2 - machine a flat disc - or someone with a laser cutter could cut a disc having glossy edges and apply a opaque clear pattern sticker underneath to possibly get a similar effect.
Option 3 - get your current insert and lay the top side of the insert down on to a flat smooth piece of steel, glass and apply heat (heat gun / good hairdryer avoiding wrecking the oven) to it to lightly soften to make the insert level out then apply a cold wet rag to secure it in shape. - Note: I have not done this to pinball inserts but have done it to plastic parts for other things, just make sure the top side rests on a very smooth surface as any crap will leave the impression on the insert.
Let me know what you want to do.
Cheers
