Den Cube is a burr puzzle with 3 pieces in a frame, designed by Osanori Yamamoto and crafted by Pelikan Puzzles. It is as much a joy to take apart as it is to reassemble.
More information is available on Pelikan's website: https://www.pelikanpuzzles.eu/detail/den-cube/
Shipping cost to be determined at auction conclusion. (domestic US shipping will likely be ~15 USD, but might change depending on buyer preferences)