To weld two or more still lifes or oscillators is to join them together. This is often done in order to fit the objects into a smaller space than would otherwise be possible. A simple example is the integral sign, which can be considered as a pair of welded eater 1s. Beehive could be seen as two welded tubs, the loaf a weld of two beehives, and mango a two loaf weld. A more complex example is the catalyst in the syringe which is a weld of an eater 2 and an eater 5.
A weld comprising overlapping unmodified objects is called a siamese object.