At first i cut out two old plates from broken "LACK" table from IKEA, so they fit in height together and screw them together. Cut out one segment of a wooden ladder in the height of the plates.

Find a an old mirror and mark the overlapping areas.

After ordering a glass cutting tool, cut the glas and don't break it. I messed it up, because the glas of my old mirror was very strong, but i tried anyways. The first glas parts came off well, but the i cracked it at the wrong place. At this point i was ordering two precut / perfectly fitted glas plates.

After having two glas plates in the proper dimensions, apply mirror foil to the bottoms glas  on the top side and on the top plates bottom side.

example of application:

Find some old LED strips (https://www.ebay.de/itm/282607930284) and find a nice plate to put them. You'll might cut them and solder some wires to the LED PCB so it illuminates the inside of the table evenly. Some of the LED-Strips have own power supply and a switch, try to re-use them here for comfortable usage.
NOTE: The mirror foil i have in use only transmits around 5% from the inside to the outside, so the LED-Strips in use can be quite bright.

Mount the light inside.

Also i bought two different PVC-pipes to put them into the table (see last picture). I was thinking about accordingly thick 90° PVC-pipes pieces, to the pot them on top of the table, so it looks like the pipes are coming out of the table into the wall next to the table, but it was not that practical in the dayli use.

Make sure the gaps anywhere stay small. Seal them up if possible. I used black duck tape for that. The top plate on my table is still not fixated, because its quite heavy and dose not slip anywhere.