I find a small black hole floating in space. It's very small, say 0.001 femtometer diameter. But it weighs about 300 thousand tonnes. It is also quite hot at about 400 trillion degrees and altogether it radiates about 4000 Terawatts of power. Apparently it will take about 70 years to evaporate. [ ref. https://space.geometrian.com/calcs/black-hole-params.php ]
I plan on maintaining the black hole's power-level and position using four cannons arranged in a tetrahedron around it. I'll put them a few kilometers away and protect them from the radiation. It seems like shooting a few cannon balls every day should do the trick?