The first step consists in setting a bucket wrapped in a plastic tarp to a bottom screwed to the box and pour plaster of Paris in the open volume. The video in the article “refitting a Warre hive” is self explanatory. The plaster hardens in a matter of hours and will cure over several days. The bucket can be removed the next morning, using a hammer to push it out. One Langstroth deep is about 42 liters, which is the average volume of a hive in a hollow tree in the wild. Usually a complete Langstroth hive is made of two deeps and one super pushing the volume to 100 liters, way too large versus what the bees will look for in Nature. Repurposing a Langstroth with plaster will reduce the volume of each deep to about 15 liters. Therefore, 2 deeps will contain 30 liters. A few liters are added with a bottom shaving box; a super would add 15 to 20 liters on top. Bees will thrive in 30 to 35 liters, they will also keep on prospering over years in a volume as snug as 27 liters, at least in the North of Mississippi. I recommend volumes between 30 and 40 liters for several reasons:

1- The control of temperature is easier for the super-organism.

2- The bee colony is rather small and in case of disease it will collapse quickly limiting the horizontal propagation.

3- The size of the colony shrinks early in the season and the queen will stop laying eggs and the comb is loaded with honey.

4- There may be an optimal ratio bee population to honey stash for winter and it feels like a 35 liter hive is right at this optimum, the stash will be full and the population sized to it.

The top bar hives are set upside down on the top box so their shape can be outlined with a sharp blade.

The grooves are carved so the triangular section of the bars can fit in, with the top of the bars flush to the plaster surface.

The surface of the inner chamber can be very slick as the plaster in contact with the plastic tarp forms a glassy surface. I use a hard metal brush to create vertical grooves similar to the grain of wood so the bees can cling but also can propolize as they see fit. A propolized chamber is necessary to the good health of the bees, it also makes the chamber water proof, conveying condensation in winter.

I like to add a bottom box to the two supers. This box is a super equipped with a tight bottom mesh to hold wood shaving. The wood shaving combined with the dejections and the moisture of the hive will eventually favor a biome of microfauna, fungi, bacteria or yeasts. This environment may be beneficial to the bees. There have been few studies on the matter, but I would believe that this box would be similar to the bottom of the cavity in a tree. Here, I created a floor board to support the bees walking into the brood chamber. The surface of the shaving is below the surface of the board. The board is slightly sloped up into the hive so the height at the rim of the cylinder is equivalent to two bees passing each other, one on the ceiling and one on the floor board.

The floor board is long enough to drive the bees within the hollow of the chamber, it is visible from above on the below picture.

The entrance is a notch of 1o centimeters flush with the outside landing board.

The second deep comes on top of the lower deep. To keep the Langstroth design, I use in this example the top telescopic board covered by an insulated roof. A quilt box similar to the one in a Warre hive can also be an option, in this case a flannel would also be laid over the top bars, a mosquito net can be inserted below the flannel so the bees  cannot chew on the fabric. You can refer to the video about repurposing a Warre hive for that matter.

The hive is ready. It is a minimum work that takes about one hour to prepare and pour the plaster and 60 to 90 minutes to build the bottom box. If the bottom box is too much work, a conventional entrance board of a Langstroth hive will work. In this case a bottom mesh with a sliding board underneath allows to count the dead mites, which is not possible with a shaving box.