Yeah, they use a 3D scanner to take a direct reading of the shape.
Got my regular soft/firm base plug yesterday and it's definitely not for the faint of heart! A bit bigger in all dimensions than my clenched fist, and it's obviously quite blunt in shape, so it takes a little work to wiggle it in. Something I was NOT prepared for is just how violently it jumps into you once you reach the tipping point in insertion. It's like getting shot in the ass by a cannonball, and the chemical aftershock of the adrenaline rush I got from the surprise actually made me nauseous, so I had to take it right out and stop. Caused some very light bleeding on account of how hard I ended up clenching on it when it jump-scared me like that. Despite that, I was feeling fine today and decided to try again, knowing how it was going to behave this time. Lubed up real good and warmed up slow, and it still startled the heck out of me, but was able to resist jumping! I was able to keep it in for a while this time, though I think it's gonna' take a few sessions for me to stretch to a level of comfort for it, 'cause the pressure was a LOT to endure and I was left feeling a bit exhausted after. But holy crap, I think once I get a bit more used to it it's gonna' be true love, 'cause it's got it in all the right places! I just need to "level up" a little before I'll be its match lol