Cut two 300 x 200mm lengths and two 100 x 200mm lengths of hardwood. Position pieces in butt-joint box shape. Drill a clearance hole into each corner of top and countersink, then drill corresponding pilot holes through sides. Drive in 75mm screws to secure top to sides. Flip assembly and repeat to secure bottom to sides.
Drill randomly spaced 10mm holes into 1 face of box. Sand area.
Cut corrugated iron to size, leaving overhang at sides to suit. Bend sheet in half widthways, reopen and position on top of box. Put log inside, then secure corrugated iron to sides of box with 50mm screws.
Put branches in hollows. Position nest in garden, elevated on existing tree stump or hardwood post. Ensure it’s close to fruiting plants or trees so it encourages bees to nest.