Purpose-built alternatives to tennis balls

Someone had mentioned lacrosse balls in a previous thread about the tennis ball trick, so I did some googling, and found some things that are tailor-made for this kind of thing. You may already know about the Prostate Cradle, but if you're looking for more intense pressure-point massages on your perineum, I'd look at these.

https://www.amazon.com/Lockeroom-Poc.../dp/B00YM5YZHI
This is wedge-shaped thing meant for getting those spots between shoulderblades, so would be great for those of us with Sitz bones too narrow for tennis balls.

https://www.amazon.com/Acumobility-L.../dp/B0752T4SY9
And this product's description directly references the tennis/lacrosse ball trick, so you know they know what people are using it for. It's also designed not to slide around, and comes pre-scented with some kind of vanilla air-freshener stuff.

There's also other things to use in conjunction with these. For example, I've gotten into pressing down on the lower end of my abs, hooking behind the pubic bone. The pincer-like pressure from both ends is real nice, but it wrecks my wrist and thumbs. Enter things like the Index Knobber and various "thumb saver pressure point massagers". There's also a thing called the Spring Thing that functions like a passive percussion massager. You press in, and the spring shaft has some give that resists more as you press down.
Using these things to massage the spot under the bone are also great during an A-session, and you might also try the rolling-pin type devices for this as well. Using a top-to-bottom motion, starting above your belly button and rolling down, lifting and repeating, you get a good massage in for the lymph nodes in this area. If you prefer the DIY methods, take all those tennis balls and shishkebab them on a 1/2"-wide rod.