For the legs, a miter glue-up with no fasteners can work. If you make a nice L-shape jig to clamp the two 45 cuts together with wood glue, it will be fine and strong. Just wax the jig. Clamp each side down on the miter, and they will press together.
Alternatively, you can miter fold the corner with masking tape, but it's not as good of a joint....more for nonstructural pieces. I've done tons of wall or desk panels this way, but I wouldn't do it for a table leg.
Alternatively, you can miter fold the corner with masking tape, but it's not as good of a joint....more for nonstructural pieces. I've done tons of wall or desk panels this way, but I wouldn't do it for a table leg.