Take 1 edge loop, cross the first 3 loops from the loops on the left needle by replacing the loop on the left with the 2 loops on the right.

and knit flat

Other loops will be crossed from right to left using the same technique to form adjacent rooms. On the back of the knitting, all the loops are knitted as purl knitting.

In the example, the point to be considered while creating the next row of rooms is that the room that was closed in the previous row will be opened in this new row. Thus, crossover is achieved.

And the finished version