Amazon.com: Base Plate Building Platforms for Building Bricks Compatible with Lego Classic, 10 "x 10" Single-Side and 10 "x 5" Double-Sides Base Plates can be Used to Build Double-Layer Buildings (Multicolored) :
4 NEW LEGO Plate 6 x 10 BRICKS Dark Bluish Gray | eBay
Amazon.com: LEGO Parts and Pieces: Light Gray (Medium Stone Grey) 6x10 Plate x10 : Toys & Games
LEGO Medium Azure Plate 10 x 10 without Corner without Studs in Center (92584) | Brick Owl - LEGO Marketplace
Amazon.com: Strictly Briks Large Classic Stackable Baseplates, for Building Bricks, Bases for Tables, Mats, and More, 100% Compatible with All Major Brands, Green, 1 Piece, 10x10 Inches : Everything Else
Lego 10x Red 2 x 10 Plate | eBay
Lego 1x 89523 Green Plate, Modified 10 x 10 Octagonal 10236 Ewok Village | eBay
BrickLink - Part 3030 : LEGO Plate 4 x 10 [Plate] - BrickLink Reference Catalog
Wedge, Plate 10 x 10 Cut Corner with no Studs in Center : Part 92584 | BrickLink
Lego Base plate 10x10 by Supersurfer - Thingiverse