im not a astronomer but i do like to keep up on the facts . fact one the nearest black hole could not be reached in anyones lifetime even traveling at the speed of light u cant slow down time realitively time is relative to the person or object that is viewing it

i have always thought that all the talk about time is kinda silly if u think about it time is just the way people quantify motion in other words if everone in ur room and every thing stoped moveing except u u might think time had stoped on the contrary their motion would have stoped

and it has not been proven a black hole is shaped like a donute , even if the singularity within was once u approched the event horizon which would be a sphere u would bee pulled to atoms once within who knows those atoms may be sreded to subatomic particals

to say u could just build a device any thing less than a antigravity device to fly into a black hole is pure fantasy plus think about radiation tempatures around it of nearly a million or more degrees and the matter traveling at light speeds falling into it