The ARM based Acorn Risc PC [1] from mid 90s had a case with up to 7 stackable slices. It made the internal volume larger and you installed a longer backplane for expansion cards.

Someone built a pizza oven in one of the slices [2]

[1] https://en.wikipedia.org/wiki/Risc_PC

[2] https://www.houseofmabel.com/personal/computers/riscpc/