We made prototypes of out frames with paper to practice cutting 45 degree angles and combining them to make a 90 degree square corner. Students then practiced cutting 45 degree angles in 2x4... it is really hard, have you tried it recently. The visual motor skills required are crazy and most of them got it after some practice. From there we moved to 1x2 and made frames for a drawing of our initials. Students had to draft their frame first and create a checklist of pieces to cut and re-cut and re-cut :) We put the frames together with brackets and screws.