A quick video showing how I picked up an old butcher block table from the garbage and converted it into a Japanese Style Kotatsu Table. Japanese Airbnb: https://www.famvestor.com/airbnb/

It's a pretty simple construction though, so you could easily make it from scratch too, just need some 3"x3" wood legs, 1"x4" Table Sides, Butcher Block Top, Dowel Nuts, Threaded Rod, and Table Corner Brackets. For the Inner Support just buy LBrackets or 3/4"x1.5" pieces of wood to make the 29cmx29cm enclosure.

* Table Heater From Amazon: https://amzn.to/2Y8MNHF
* Too lazy to make a table, buy one here: https://amzn.to/2POBRMl