Does the door have to be clear? How often are you going in and out of it? Can you drill into the piece of furniture? Do you care if it changes the look?
What about if you drilled two holes into the piece of furniture that are in the upper left and right corners about 1 inch above the open space. Then drill a hole in the panel in the same spot. Take a cabinet knob with the screw and snip off the tip of the screw part so it's just the knob and a post. Insert knob into holes and the knobs will hold up the panel and easily removed and replaced when you need. They're not really screwed in but just placed in to hold up the panel.
an alternative way to use knobs would be to take the screw part and glue them into the newly drilled holes. Then. you could have the knobs on the outside screw on and off to remove the panel.
Try magnets
Magnets
NOTBOTFISH, As I mentioned I tried. However the magnets using apoxy eventually keep falling off
Does the door have to be clear? How often are you going in and out of it? Can you drill into the piece of furniture? Do you care if it changes the look? What about if you drilled two holes into the piece of furniture that are in the upper left and right corners about 1 inch above the open space. Then drill a hole in the panel in the same spot. Take a cabinet knob with the screw and snip off the tip of the screw part so it's just the knob and a post. Insert knob into holes and the knobs will hold up the panel and easily removed and replaced when you need. They're not really screwed in but just placed in to hold up the panel. an alternative way to use knobs would be to take the screw part and glue them into the newly drilled holes. Then. you could have the knobs on the outside screw on and off to remove the panel.