Due to the small dimensions of 1515 aluminium extrusions, you may be hard-pressed to find T nuts that are commonly used in larger sized extrusions. Normal M3 hex/square nuts are therefore the most commonly used.
One of the most common problems when handling hex nuts in 1515 extrusions is that they are loose and slide along the extrusion slot. This becomes tricky when attempting to align multiple nuts with the through holes of a printed part. Here we present a few tricks to help with this problem:
Use a thin hex wrench and magnetize the tip with a magnet (you will probably have magnets already in your voron kit). You can now both push and pull your hex nut easily along the slots of your extrusion with the hex wrench.
Another great solution is to print your own T nuts. Zen3D has this great user mod that combines a normal M3 square nut (or hex) with a small printed part to create a "T nut" that fits snug into 1515 extrusion slots.