If you have a laptop, and have or can borrow a computer projector, then you can project a silhouette of the critter of choice onto a wall.
For silhouettes, simply google words like "deer silhouette", and click on the "images" tab, and you can get many versions and angles of animal silhouettes. Some are proportionally accurate, some are not. But there are many to chose from.
On the wall you can tape up wide sized sections of wrapping paper large enough for the critter you want.
Use the zoom on the projector lens, or move the projector back and forth to get the scale size you want.
Trace the projected silhouette on paper and cut it out.
Now you have a tracing pattern to trace onto a plywood target. Cut out with a jigsaw. Make a stand for it.
A buddy of mine made a scale moose target this way. He scale sized it to fit the plywood he had. He cut a hole in the heart/lung area, and hung a steel gong in the back of it.