If the cigars are to be kept in their boxes, there is already enough spanish cedar there..... Then I would go the easy route, and have shelves cut out out plexiglass.
If you are going to have singles and all, different opinion.....sorta..... Spanish cedar is not cedar, it is a type of Mahogany. Luan is also Mahogany, and is quite easily found. So you could use Lauan or Honduran Mahogany no problem...
By the way, just FYI, I found on Amazon a 2x4 piece of 1/4 inch spanish cedar plywood for 38.39$, shipped free to your location. This can be cut in a couple shelves.
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To be honest, if you plan on keeping the cigars in their boxes, and possibly use empty boxes to store singles, you'll have enough spanish cedar for aroma and humidity buffer/regulation. Then, I would make shelves out of acrylic (plexiglass). Can be found and custom cut pretty easy, weighs next to nothing, and can be bought clear or in various shades of color. Could be perforated to help air circulation if needed. You could glue strips of plexiglass to make dividers for singles, endless possibilities.....
There is a Zino Humidor made exclusively of plexiglass...
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Just my two cents....
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