fabian-ang [1] filed an orphan request for teensyduino [2]:

Package was not updated for over a year. There are already 2 new releases of this software that were released after the last update. It was marked out off date 4 months ago. Also the current package does not build.

[1] https://aur.archlinux.org/account/fabian-ang/ [2] https://aur.archlinux.org/pkgbase/teensyduino/