I have used several different prostates massagers with vibration features (including other prostate sex toys including the njoy Purewand Stainless Steel Dildo and several Aneros prostate massagers) and out of all of the prostate massagers that I have used this is the best:
Lelo Loki Wave 2
It honestly is fantastic and perfectly designed to stimulate your prostate (in the specific pushing motion that works best) to make you have prostate orgasms! There is a prostate orgasm topic we have been discussing for a few years which has all of our thoughts and best tips for having prostate orgasms:
Personally, I have used prostate massagers that clearly were not designed to give the user a prostate orgasm (these are normally the vibrator ones) so I really think specialising and focusing on a prostate massager that can help as many people as possible have prostate orgasms (and to raise awareness in general about prostate orgasms, not enough people know about them or even believe they can happen) should definitely be the focus!
In terms of the size/shape/stimulation the Lelo Loki Wave 2 does everything perfectly so that is exactly what I would recommend for the design, but the real trick that you could do is to make your prostate massager specifically for people having their “first ever prostate orgasms” and include a guide that provides information/advice and very detailed step-by-step techniques so that anyone can do it!
I would be very happy to help in anyway I can (I am a BIG advocate of prostate orgasms, having only discovered them myself a few years ago and being an advocate raising awareness about how amazing they are for people who have lived an entire life only having penis orgasms/singlular orgasms) so do let me know if you would like any support and I would love to help you create a prostate massager that could really enable more people to experience these amazing prostate orgasms! 