I've set up a new mastodon instance. It is named Plethodon after the genus name of the North American woodland salamanders, and it can be found at http://plethodon.nl
I also added some buttons to my three instances (peertube, mastodon, lemmy) so that it is easy to jump between them. You can find them in the header of mander and the sidebars of the other two instances.
Unfortunately, it is necessary to create an account for each project. I will try to find out how to create a single account for the three in the future.
It would also be nice to find a way to integrate the three applications into a single site - similar to what @ernest@karab.in is doing at https://karab.in/.