I only spent about $60 on it and a couple of hours!. Lay your 1x3s, 1×6 and 1×8 down and arrange for square. Web diy grid mirror from mirror tiles.
Diy mirror casing frame
Diy mirror in ready made frame
Diy clay mirror frame
20++ Diy Mirror Frame Decorating Ideas HOMYHOMEE
Web build the mirror frame.
If you have a kreg jig™, screw the 1x3s to the 1×8 and 1×6.