A masochist wall-bracket...

You'll (no doubt) know this bracket, intended for the spare roll of toilet paper, (which oftenly is inaccessible when needed)…

It can however be used for wallmounting a masochist !
Find one which is mechanically stable enough ! !

Then you measure your partner, from the floor, to the vagina/anus, while standing at full attention.
Then you mount the bracket on the wall, so that your partner will have 4/5th of it inserted into the body cavity in question, when riding the bracket.

Apply a condom, and in case of an anal insertion, a little KY.

Place a stable box under the bracket, and let your partner step up. Then it's just to insert the bracket, and tell your partner to (carefully) step off the box - which you then remove, and BINGO….

And now a version to bring to the local swinger/SM-club: