When I was in grade school (St. Wenceslaus) I designed a ray gun and asked my science teacher (Mr. Belsito) if it would work.
Put a large, mildly convex lens in sunlight. Just before the focus, put a small, strongly concave lens to cancel out the converging and make a beam. Aim with a mirror.
Mr. Belsito said that of course it would work, that's how lasers work.
Was he right (about it working, not the laser part)?