A very simple mount plate to attach the LLL filament buffer in vertical direction on an horizontal extrusion profile.

To mount the filament buffer to the plate you need two 12mm M4 bolts and nuts. To mount the assembly to the 20x20 extrusion you need two 8mm M4 bolts and T-nuts.  I used in on an TRONXY X5SA 400Pro printer (heavily modded with Klipper, not really relevant) and used the existing 8mm M4 bolts and T-nuts from the original extruder/sensor mount. The pinout matches that of the TRONXY, so I just replaced the original filament runout sensor (which was giving me random disconnects). You may have to prepare your own cable for your printer.