There is not really that much difference between an air compressor and a vacuum pump, except maybe which end of the machine the hose is being used on, being on the end that sucks instead of blows.
You can build a simple homemade vacuum pump, using a barrel of water with a spout or bung, one at the top and one on the bottom of the barrel, the bottom valve is to let water out of the barrel, the valve at the top of the barrel is used to fill the barrel with water or for the vacuum hose attachment.
From this closed barrel full of water, opening the bottom valve the water drains from the barrel by gravity, the barrel being closed begins to pull a vacuum from the top valve, a hose attached to the top valve becomes a suction source or vacuum, this vacuum will continue as long as there is water being drained from the main barrel
by using another barrel that can act as a receiver or storage container for the water to drain into from the first (vacuum barrel), and you can then reuse the water from this second barrel to re-fill the first working vacuum barrel, you can use a pump or just transfer the water or just transfer the water by hand from the receiver barrel back into the main vacuum barrel.
