A new model is available in the Model archive. I converted this over from an old Poser/Daz model to use on the new render.
It has super basic materials so feel free to customise. It has a rig for moving the 'whole' object. The wrench when selected will show 2 properties in the 'N' panel to allow you to change the 'hole' type and if the cap should be on.
The 'ring' allows you to 'open' the hole. This is controlled by shape keys but the 'ring' will automatically swap to control which ever 'hole type' you have selected.
Hope it is useful. I might improve it to work with a proper UI made using Python at some point (probably extending Crute's from his dong on Smutbase). I wanted to release it on here in case it was useful. When fully done I might release it to Smutbase if someone else doesn't beat me to it.
Note: Should be up in the Model Archive now. Check the 'Archive' category here on Patreon to find the latest link.