Sheikh `Abd al-Rahmân al-Barrâk
If the design explained in this question is made to honor the deceased or in order to prevent soil from falling upon the body, then this is indeed something that emulates the ways of the unbelievers who put their deceased in boxes or build something like rooms for them.
However, if some cement is placed around the deceased to harden the soft sand around him so that the ground will not collapse, then it is alright. Building blocks may also be used for this purpose if there is dire need.
In case of normal hard ground, a hole should be dug and a slot should be opened to put the deceased within it in accordance with the Sunnah the Muslims should follow.
And Allah knows best.
Source: Islam Today