I'm at the cusp of 3 1/2 inches, after several years of dedicated pursuit. I tend to use found objects as toys.
My last big splash, a black Kevin dildo, seems to be too long/firm at the top for my ass to reach the knot at the base. Considering how durable the tissues are in tension, it's worth trying a little harder next time. I do enjoy the crazy desperate feeling pushing at something obviously too wide to go in (and later amazement when it finally does.)
My preference at the moment is for unripe grapefruit, readily available a few steps from my door. These are usually oblate, so they are easier to put in sideways compared to end-on. Stored in a cupboard, they slowly shrink, so that something impossible now can later be accommodated. Once it fits the easy way, I can try it end-on for an extra stretch.
Each grapefruit will last for a month or so. Recently I took medium and large ones. The sizes are right but they have a rough texture that makes it challenging, because you have to expand your ass to reduce the friction and allow the toy in.
I find each increment in size comes when I'm able to let my ass muscles release in a new direction. For me the process is mental as well as physical. To get a new, larger object it, it helps me to build up successes with something smaller and visualize the new, huge thing inside my ass. I pucker my mouth and push my lips forward as a way of encouraging my ass to do the same.
You have a choice when pushing a toy into your ass. You can let you ass accept it passively, or you can push your ass toward the toy, which also helps widen your ass. I love to go slowly, both going in and coming out, lingering with the widest part of the toy in the narrowest part of my ass. In the midst of this intense sensation, I remind myself, "This is what you wanted" and allow myself to feel deliciously slutty.
Is it safe to use a toy without a string to pull it out? You use diaphragm pressure to push it out, just like a turd. If your ass can stretch to allow something in, it can stretch to let the object back out. The only caveat I've found is that for 3-inch objects, I need to help with my hands to release the folds of ass from around the toy. A better lubricant might help with that.