in the bottom left-hand corner of a wooden board, draw a square the size of the motif (i.e. 15.5 cm -0.5 cm margin) plus the width of the frame edges (2.5 cm), i.e. a 20 cm square, then a second identical square side-by-side. Draw a reindeer antler on a sheet of paper (cartoon-style, I agree).
When you're satisfied with the design, transfer it to the wooden board above the second square (it seems that leaving a 3-4 cm margin from the edge is prettier), then invert the sheet of paper on the other side of the square.
Finally, I've chosen to round off the bottom edges of the frame on one square (once you've cut out this square, you'll transfer these roundings to the other).