The Netbox community has launched a repository for standard devices.
This comes handy for new and existing Netbox installations, because now you can populate your database with predefined device models for the most common networking gear manufacturers.
I have contributed to the repository and created the entire set of MikroTik routers and switches, updated to December 2019.
Feel free to use it and contribute!
And as always, you can find me on Github at https://github.com/baldoarturo