You'll need

Item Material Measurement

Mirror frame sides (2) 40 x 19mm timber cut and planed to 700 x 35mm
Mirror frame top (1) 115 x 19mm timber cut and planed to 325 x 100mm
Mirror frame bottom (1) 65 x 19mm timber cut and planed to 325 x 50mm

You'll also need: 8mm dowel cut into 8 x 40mm lengths; waterproof epoxy resin (if using in bathroom) or PVA glue; mirror glass measuring 342mm x 616mm; 3mm-thick plywood or MDF measuring 345mm x 620mm; 120 grit sandpaper; polyurethane gloss varnish; panel pins.

Tools
Handsaw or circular saw
Smoothing plane
Jigsaw
Router with straight bit and 12mm round-over bit
Electric drill or dowelling jig
Electric sander (optional)

Here's how:
1. Cut and plane the timber to the correct measurements. Click on the illustration at the top of this page for a full-sized diagram.

2. With a jigsaw, shape the top piece, making it 50mm high at the ends and the full 100mm height at the centre. Similarly, round off all the corners.

3. Using a router with a straight bit, cut a 10mm square rebate into the rear inside edges of each of the four frame components to take the mirror glass and back. Make the corner joints by drilling holes for two dowel pegs into each one. A dowelling jig will ensure accuracy. Now glue and assemble the frame.

4. You can simply round the front edges of the frame with an electric sander, but for a better trim, rout the edges with a 12mm round-over bit. Sand and triple-varnish frame.

5. Have mirror glass cut to size and fit 3mm-thick plywood or MDF inside the back rebate. Use panel pins tapped into the inside edge of the frame to hold the back in place.

Source:The Complete Home Improvement Book (Murdoch Books)