We use those stick-in-the-ground political signs that politicians put on roadsides and lawns every election cycle - the kind with wire frames with a corrugated plastic sign on top. We use clothes pins to secure the target paper to the sign. I collect a good supply every election cycle. On our club's rifle range we have one or two of those signs at various distances from the bench (25, 50, 75, 100, 150 and 200 yards).