If you don't have heavy metal weights for your gym, you can use concrete and big rocks chipped to the correct form. Here is are some make-shift weight lifting dumbbells found in the Garrido Boxing Gym in Sao Paulo Brazil. Notice the tidy wooden pallet to keep the weights off the floor. The gym occupies a left-over space under a concrete highway flyover. The picture was taken by Jan Chipchase from his blog Future Perfect.