Wow, Anne, that's an amazing description. Hope everything came out OK.
Sorry, I couldn't help myself. 😜
For gizzmo - I think experience and gravity have more to do with your control than size of the object. However, size can be a factor in ease of insertion and/or expulsion.
I recently purchased a steel plug with a glass 'jewel' on the base. I used some silicone lube because it lasts a lot longer than KY or vaseline, and the 1 1/2" diameter bulb slid right in with only a little preliminary pushing and pulling. God, that felt so wonderful, spreading my anus to accept it. The shape and smoothness prevented any need to force it inside.
It was at room temperature so it felt cool during and just after insertion, but soon warmed up. I was a little concerned about what the tapered end might do becuase it was just that - tapered almost to a point. However, the plug was so well machined and polished it did no damage.
My anus clenched the narrow stem between the bulb and base easily because it is a mere .375" diameter, less than half an inch. At 1 1/2" diameter there was no way it would accidently slide up inside my rectum once the sphincter locked around it. The base, too, is so well polished it didn't dig painfully into my ass cheeks, but I do feelt it.
This little gem weighs in at just over 11 ounces, so gravity played a big part in the episode. As Anne pointed out, any pressure on the sphincter makes you feel like you have to poop. 11 ounces of steel gave me that feeling almost immediately.
I think I finally gave into the need in less than 10 minutes and headed for the john. Warning: this is made of steel, so if it hits the inside of a ceramic toilet the toilet is going to break, so be carefull when removing it.
There are three things I would change.
* One - a slightly larger diamter of, say, 1 3/4" with corresponding increase in length.
* Two - a narrower base so the cheeks can close a bit more. Maybe 1 1/2" long by 1/2" wide. If a jewel is desired apply three smaller ones along the length of the base.
* Three - Someone to help out. Sorry guys, I'm straight, so it would have to be a woman. 😉