Making Icons is hard work especially if you have to get transparent and quality images, on AROS One the Folder Icons are 780, then consider that I created 4 styles for a total of 3.128 Folder Icons
Usually when you reduce images there is a loss of quality, I usually to have no loss of quality I use as "Zoom" the Windows folder, which in the reduction (mouse wheel) reduces with less loss of quality.
The best trick to resize images is to cut/paste by shortening and tightening the images, this greatly decreases the loss of quality.
Indeed it is hard work. It requires many hours to produce quality icons. It's not easy to find or make graphics which scale nicely and look good at icon dimensions. Some need to be "stylized" to make them into an approximation of the real images. The icons are merely symbolic representation of everyday objects or tasks. The more color, the better!
Once I get a complete set of icons that I like I can use HSL Color Rotation to produce more color variations. Overlay masking is useful for automatically copying the images to new colored folder icons. Automation is good.
The folder icons will be slightly larger than project icons for visual effects. The project icons are just 46x46 squared Icons usually with a white background but colors vary. I wanted the project icons to be drop-in replacement for PNG Glow Icons such as Kens Icons. They are interchangeable.
The icons that I'm developing for AROS are heavily influenced by the look and feel of early Mac OS X icons, especially the powder blue folder icons. But the graphics also resemble the Faenza Icons for Linux. But as far as I know Faenza are only single PNG or SVG images and they are much larger and different than 46x46 PNG Glow Icons.
Like AROS which has one foot in the past with its Amiga roots and an eye towards the future with a synthesis of things classic and things modern so are the new icons. The PNG icons are modern in appearance but they will be influenced by Classic Amiga Glow Icons from OS3.5/3.9 and especially the visual style of AIAB ( Amiga In A Box ) which used Scalos.