or confine it right and not make it massive enough to kill us
but if you’re trying to make it light enough to carry, it’d also need to be created in the container which it’s confined in, since if its confinement breaks, it would immediately explode hard enough to scorch half the earth, and cause an earthquake of at least magnitude 11(assuming somewhere in the decagram range), if on the earth when it explodes, since evaporating a black hole is a 100% efficient way to turn mass into energy
and we’d also need to make sure the black hole’s confinement is perfectly reflective to the wavelength the black hole emits, since you’re basically trying to confine an explosion on the level of a matter-antimatter annhilation with the mass of the ringularity, constantly
however, a black hole with the earth’s mass would last 1.8 * 10⁵⁸ seconds, or 1.3698630137 * 10⁵² years, which is far more than long enough to confine without worrying about effectively trying to contain an antimatter bomb that’s constantly exploding(and you only need it to last 1 second to do that), and it’d release the equivalent of 4.35956e-28 kg every second, or 1.3069632082x10¹⁹ watts[1], so it’s cold enough you don’t even have to worry about the energy it puts off(you only have to start after it reaches somewhere well over 5), so you can probably use a ringularity weighing only 10¹⁰ kg [2], and 10¹⁰ kg is small enough you could theoretically survive near it, and assuming TO goes through the center of a ringularity with a diameter of 6 ft, they would experience an average of 54.31 newtons towards the edges of the portal, while going through its center(though, that’s calculated using point masses, so it’d probably be less, and whatever diameter for a cylindrical segment of the ring’s confinement lets TO not lose a leg by stepping on it[3] could be used to make sure the portal is traversable(probably means that portals will be at least several meters wide, if living creatures are supposed to pass through, though 10¹⁰ might still be a bit heavy for a black hole in a portal, and a 1d mass will necessarily be less dense, and thus have less gravitational pull, than a 0d mass)
though, that does still leave you with the problem of getting something that light to form a black hole in the first place
tho it’s probably less, since that’s the average over its whole life ↩︎
for reference, using point charges, at 0.8m from a singularity weighing 1¹⁰kg, TO would experience an average of 70.95 newtons, so that’s probably gonna be the minor diameter of the confinement for a ringularity with said mass(but again, the math was done using point masses, rather than with circular and point masses, so it’s probably way less than that) ↩︎