Mount the arch to your wall using a wood glue like Liquid Nails Heavy Duty Construction Adhesive at a bit under $4 for a 10 oz tube and a nail gun. Once the arch is secured to the wall, use a ...

Constructing an arch bridge can be tricky, since the structure is completely unstable until the two spans meet in the middle. One technique is to build elaborate scaffolding, or "centering," below ...