It would probably help if we knew what your goal is. Have you not found a but plug large enough for your liking? Or perhaps long enough? If so, I have experienced this same agrivation. A very large dildo may work nicely if the reciever is well lubed and you work up in size slowly. But of course, you can not keep it inside on it's own the way you can with a but plug. I am sure there must be a limit to the width you can stretch it, but I do not know the exact answer.

For your second question - How small are the items you are planning on inserting into the vagina? Something the size of a small tampon (about 2 inches long and thin) can be easily removed by baring down with the aid of a finger.

Personally I have had a raw egg carefully inserted in my vagina and with just a little push it pops right out.

Slave Nastia