Creating any number of RNodes is completely free and unrestricted for all personal, non-commercial and humanitarian purposes. Feel free to use all the resources provided here, and on the unsigned.io website. If doing so provides value to you or your community, you are encouraged to contribute whatever you find to be reasonable.
The RNode Ecosystem is free and non-proprietary, and actively seeks to distribute it's ownership and control. If you want to build RNodes for commercial purposes, including selling them, you must do so adhering to the Open Source licenses that the various parts of the RNode project is released under, and under your own responsibility.
The RNode Firmware is released under GPLv3, and basing commercial works on it means (among other things), that you must also make your derivatives open source and available under the same terms.
In practice, this means that you can use the firmware commercially, but you should understand your obligation to provide all future users of the system the same rights that you have been provided by the GPLv3.