Rudimentary router sled, for rough flattening materials too wide for a thickness planer. : r/woodworking
Router Leveling Jig | Woodsmith
How to flatten wood with a router [Complete guide for beginner]
Router Planing Sled | Woodhaven
Slab Jig – Router Sled for Woodworking – Levels Wood Slabs Up to 64 Inches Wide! Portable, Durable, and Easy to Adjust! Great for River Tables and Home Improvement Projects! : Amazon.ca: