It is square-based and open-sided, usually with twelve indented corners, with four posts supporting a roughly pyramidal multi-tiered roof culminating in a pointed spire, and usually richly decorated.
The structure of the multi-tiered roof is very similar, but much smaller in size, to the mondop architectural form.
[1][2][3] The term is derived from the Sanskrit word puṣpaka, a reference to the Pushpaka Vimana, a flying chariot from the Hindu epic Ramayana (and the Thai version Ramakien).
[6] Smaller busabok are used to house objects associated with the king—an early documented example was used to carry the royal letter of King Narai to Louis XIV in the 1686 Siamese embassy to France.
Very large versions have formed the design of the temporary crematoria used for royal funerals of previous kings.