2x2 Gridfinity flux holder. It stores 2 flux containers, and a small amount of whatever accessory that you need. I use my extra space to store a few cut up q-tips to use as flux applicators.

This is designed to hold flux that was purchased from the following link. https://www.amazon.com/dp/B08MVXW4RY?psc=1&ref=ppx_yo2ov_dt_b_product_details