Small 1.5cm offset piece for a cheap Amazon keyboard tray slider to facilitate a synthesizer. Basically lowers The tray a bit to accommodate the knobs I swore would fit when I measured everything initially.
Nothing special. You will need longer wood screws to accommodate the extra length. Obviously use at your own risk (like I am).
This was the tray I used but I think they are all basically the same.
https://www.amazon.com/FRMSAET-Thickness-Construction-Accessories-Furniture/dp/B07H9XXWFW
The author marked this model as their own original creation.