Before cramming Junior’s finger painting into a frame that’s too small or letting a concert poster swim in one that’s too big, consider a sectional-frame kit. Available in inch increments between 8 and 40 inches, the kits allow you to pick a size that is perfect (or will be after a little trimming of the piece). There are two “sides” in each kit, so you’ll want one for the length and one for the width.

What You Need

Nielsen Bainbridge frame kits ($8 to $17, www.dickblick.com)

Flat-head screwdriver

Piece of glass (prices vary; art-supply stores will cut to size for a small fee)

Foam board ($7 for a 30-by-40-inch piece, www.aifriedman.com, art-supply stores)

Utility knife, for cutting foam board (about $6.50, art-supply stores)

How to Frame It

Step 1: Assemble three sides of the frame by connecting a shorter section to each end of a longer section. Use a screwdriver to tighten the joints.

Step 2: Sandwich the art between a piece of foam board and a piece of glass (both cut to the size of the artwork), then slide them all into the metal frame.

Step 3: Turn the whole thing upside down, and attach the fourth side of the frame, tightening the joints with screws, as before.

Step 4: If there’s a lot of wiggle room and the artwork and glass are rattling around inside the frame, use the included pressure clips to keep everything in its place.