I recently got my Samsung Active Smartwatch and got to building a charging stand.
I found Roman2W's design for the Gear S3, however, needed some adjustments to allow for the different wireless charger.
Made with 3mm plywood, I made sure to cover the timber with masking tape to avoid burn marks.
To prevent the charger from coming loose during use, I placed a Neodymium magnet underneath. In the future, I might figure out a way to weight the base more.