The basic construction is as follows:
Find a coffee table that is constructed with a basic external frame of the sides and legs, plus an inserted top of some form. The top needs to be screw fitted to the frame so that it easy to remove, or could be glass, which could be reused.
Remove the original top.
Remove brackets/beading to which top was fixed, if not in a suitable position to mount a glass top.
Re-fix or replace brackets/beading at a lower position, or extend beading with stained wood of suitable dimensions. I used a depth of 1" for the internal gap between the bottom of the cabinet and the bottom of the glass cover.
Fix the original top, or new base board if the original top was glass, covered with a suitable display material, to the underside of the brackets/beading. I used some material from a pair of old velvet curtains purchased from a charity shop.
A toughened glass top can be purchased, if necessary, to fit loosely on top of beading, but think about how you will lift it, something I forgot to do! As the glass top is toughened it is not possible to drill it later, so adding a knob or hinges would have to be done at the manufacturing stage.