Hello, thanks for a great mod. I'm currently doing something myself and looking for GUI icons to borrow from other mods. In particular, I need those round-robin/random distribution icons. I also saw the same icons in Thermal Dynamics. The latter has the following notice in their repo:

Art and sound assets are released under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0), a summary of which can be found at: https://creativecommons.org/licenses/by-nc-sa/4.0/

©2012-2017 Cult of the Full Hub / Team CoFH / CoFH

Though, I'm not sure this license applies to those few icons in particular, or are they borrowed from elsewhere. I'd like to ask developers of Refined Pipes, if you remember where you got them from and how they are licensed. And, if it's from Thermal you might want to add attribution/license reference because the license mentioned above demands so:

Attribution — You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.

If supplied, you must provide the name of the creator and attribution parties, a copyright notice, a license notice, a disclaimer notice, and a link to the material. CC licenses prior to Version 4.0 also require you to provide the title of the material if supplied, and may have other slight differences.

I think I took the icons from CoFH, but never gave attribution as I didn't put much thought behind those icons, as they were intended to be temporary. I will update them later.