To start you will need two MDF layers that match in size and 4 strips of wood to make the sides.
Measure the sides
Mark the right size
Cut the wood to size
Mitres are angles of 45 degrees
Use the angle guide on the bandfacer to make your mitre corners
The angles should point towards each other - like a triangle
Two sides need to be shorter
cut them down to fit inside
The sides 'butt up' to each other
this shows how a butt joint looks
lift each piece individually to add glue
Use a glue stick - NOT A PAINT BRUSH!
Glue all the sides and add glue to the mitre corners too.
Attach all of the sides with glue
Glue the top on
Put your box in a vice and close it gently.