What's the Best Material for Picture Frame Backing and What Holds

Hi guys! Just a quick question or two I hope someone can help me with. I'm making a last minute picture frame as a holiday gift, and I'm not sure what to use for the backing board. I'm talking about the material that holds everything in the frame, not the matte for the photo or anything like that

Backing Boards

What's the Best Material for Picture Frame Backing and What Holds it in Place? - General Woodworking Talk - Wood Talk Online

Picture Frame Backing Board Options

Vintage Frame Single Label – EverEmblem

Picture framing for beginners

What is a Backing Board?

How to Frame a Puzzle – Love & Renovations

WF-426 DIY Wood Frames (Frame Only) 48x24x6

Picture frame backing and easel stands

Vintage Heirloom Frame for 13x10 Picture Pre Owned

How to Hang a Picture: 5 Tips for Hanging Photos on the Wall, Architectural Digest

How to Add Glass and Art to a Picture Frame - FineWoodworking

Annecy 5x7 Picture Frame (4 Pack, Distressed White) - Rustic 5x7 Photo Frames with High-Definition Real Glass - Wall Mount & Table Top Display