Plexiglass is a thermoplastic material that is heated to a soft consistency and cooled back to a solid state. For this reason lighting and illuminating an etched piece of plexiglass requires some care in order to prevent overheating the piece. You can get around the heat issue by employing cool LED lights set discreetly below the plexiglass. The light illuminates the glass by reflecting off the etchings you made. You can etch just the edges to illuminate the entire piece or scribe a design in the plexi for more a elaborate subject for illumination.
Stand the plexiglass on top of the block of wood and trace the footprint with a pencil. Make sure you draw the line along both the front and back of the plexi piece for an accurate footprint.
Calculate the depth of the groove you need in the wood. The depth should be the thickness of the LED light rope plus 3 inches to hold the plexiglass.
Router a groove within the traced plexi footprint to the depth you calculated. Make sure the groove is exactly as wide as the foot print or the plexiglass will not stand up properly.
Drill a small hole at one end of the groove going vertically downward through the block. Route a small groove on the underside of the block from the drilled hole to the edge to allow the light an exit path to connect to an outlet.
Feed the end of the light rope up through the bottom of the block in the drilled hole. Pull the rope through enough that it lies across the entire groove on top of the block. Push the rope into the groove on the bottom of the block so the wood can rest flat on a table.
Push the plexiglass into the groove on the top of the block so it is resting on the light rope. Connect the light plug to an electrical outlet to turn the LEDs on.
Look for LED light ropes around Christmas time or in decoration supply stores.
Do not use untreated wood for the stand or it may become damaged by the lights.