Determine whether the photograph and its mat board are "true" with 90-degree corners - if not, decide how you will compensate for the irregularities. Gauge how many feet of poplar you will need for the frame you are making. We have decided to make the frame of solid poplar in three different thicknesses (1/4, 1/2, and 3/4-inch), and all available at the local home improvement center. Measure the outside horizontal and vertical edges of the photograph and mat (for a rectangular work, you will have two different measurements for the sides versus top/bottom) and then add twice the width of the finished molding to each for an approximate finished length. Purchase four pieces of poplar in each of the three thicknesses and allow plenty of extra length on each of the 12 pieces to miter the ends.