The word 'makeshift' has a couple of uses: 1: done or made using whatever is available; 2: something contrived to meet an urgent need or emergency
The boards and cinder blocks are only a makeshift until the bookcase arrives.
She made a chain of cans on strings beneath all of the windows as a makeshift burglar alarm.
The synonyms include improvised, jury-rigged, contrived, provisional, or temporary.
A makeshift raft floats by virtue of the bouyancy of the materials used to build it. The builder makes it out of stuff that floats. Given a choice, it would be better to make it out of logs rather...