I have used the plastic push-in ("removable") rivets sold by Giant Leap Rocketry
(scroll to the bottom of the "Recovery" page to see them). I have used the small rivets to attach a nose cone to a payload section in one rocket and to affix interchangeable motor mounts in another one. I also have a set of the large rivets, but I haven't built anything that needs them yet (they are quite beefy and strong).
I use the small rivets in multiples, spaced evenly around the airframe. I used 5 rivets for the nose cone (in a 2.6" diameter airframe), but now I realize that it was overkill to use so many; 2 or 3 would have been quite sufficient. I am planning on using 2 or maybe 3 to hold in the motor mounts in the other rocket. I am using them to keep the motor ejection charge from ejecting the mount; the mounts are restrained from moving forward under thrust by sturdy thrust blocks. This is a mid-power build, and if I had chosen to use them, the large rivets sold by GLR would
hold the mount in place and keep it from moving forward under thrust from an F or G motor; they are that strong.
GLR's small removable rivets are the same as the "click-lock" type of plastic push-in rivets shown at the McMaster-Carr site, while their large rivets are the same as the "expanding" type at MMC.
Both types truly are removable and reusable. The entire head of the small click-lock type is pushed in and pulled out to lock and unlock the rivet, and both operations can be done by hand. The large or expanding type has a pin (actually, it resembles a nail) that pushes in and pulls out of the center of the rivet's head. It can be pushed in by hand if you have strong thumbs and a fairly high pain threshold; otherwise, use something hard to push it in. Do not try to tap or hammer in the pin; not only is it not necessary, but it also can cause damage to the surface of your airframe. Most of the force is needed just to get the pin going for the first fraction of an inch, until it has started to spread the prongs on the other end. The reason that you will probably need to use something hard to push it is because the head of the pin is small and it will put a nice dent into your thumb otherwise. You will then need to use the flat blade of a screwdriver to pry the pin back out when you want to remove the rivet. In both types, first you push the rivet body into a hole that you have drilled, and once it is fully seated, you push in the head or pin to lock it in place.