The trick of making a mold would be interesting, i wonder if a two component material can do it.
For making a mold of my ear to make ear protection they used a two component material which looks like a latex made thing.
Cure time about 10 minutes
Gone try and find out what material this is, wil be back on that.
A other thing we may need is a thin tubing preferible made of somekind of foil to put the two component stuf in to not damage the urethra.
And do not forget a fail safe wire for retreaving.
Edited; the latex stuff is in reality a silicon based paste made by DETAX.