Here’s a bit of fun, for which I thank my excellent friend Tony Piper. It’s a self-boring coffin, hermetically sealed, with built-in flower and flag receptacle. Two people can (er, theoretically) screw it into place like a capstan. It was patented in 2007, since when there seems to have been little uptake (wrong noun, surely?).
Like all the best ideas, it is limpidly beautiful. Contemplate the detailed plans here.