How to Trace Stained Glass Patterns Through Glass (Light Box Method)

This is the third way to get a pattern onto glass, and it's the simplest in concept: put the paper pattern under the glass and trace what you see. We've already covered the label paper method and the marker tracing method in earlier guides. This one works well for clear or light-colored glass without any extra tools, and with a light box, it works for darker glass too.

This guide walks through printing your pattern, tracing it through the glass, cutting along the marked lines, and grinding the edges smooth. If you're working from one of our beginner pattern kits, the numbered cutting template is sized and scaled for exactly this workflow.

What You'll Need

• A downloaded pattern kit (numbered cutting template, color mockup, and cut list)
• Regular printer paper
• A printer
• A light box or light panel (only needed for darker or textured glass)
• A fine-tip permanent marker
• Glass cutter and running pliers
• A glass grinder or hand sanding stone
• Safety glasses and cut-resistant gloves

Step 1: Print Your Pattern at Actual Size

Print the numbered cutting template on regular paper, not the color mockup. Set your printer to 100% or "actual size," never "fit to page." Check the printed page against the scale reference in your kit before you start tracing, so your finished piece comes out true to size.

Step 2: Cut the Pattern Apart, Piece by Piece

Cut each numbered shape out of the paper pattern individually, keeping the number visible on each piece as you go. Working piece by piece, rather than tracing the whole pattern at once, keeps your glass color choices organized and matches how you'll cut and grind afterward.

Step 3: Position the Pattern Under the Glass

For clear or light-colored glass, this step is simple: lay the paper piece flat on your worktable, place the glass directly on top, and check that you can see the pattern lines clearly through it. Good, even lighting overhead makes a real difference here.

For darker, textured, or opalescent glass, the pattern lines usually won't show through on their own. This is where a light box comes in. Turn the light box on, place your paper pattern piece on the surface, and set the glass on top. The backlight pushes enough light through even fairly dense glass to make the lines visible.

If you don't have a light box, a bright window works in a pinch, though it's harder to control and not something we'd rely on for a whole project.

Step 4: Trace the Pattern onto the Glass

With the pattern lines visible through the glass, trace along them with a fine-tip permanent marker. Move slowly and keep the glass from shifting as you trace. It's easy to lose alignment partway through a curve if the glass slides even slightly.

Write the piece number on the glass itself, off to one side, before you move it. Once you lift the glass off the paper pattern, that number is the only thing telling you which piece you're holding.

A few things that make this step go smoother:

• Use a fine-tip marker. A thick line adds imprecision you'll have to grind out later.
• Trace on the top surface of the glass, and keep that orientation consistent across all your pieces.
• Work in a stable spot where the glass won't get bumped mid-trace.

Step 5: Cut Along the Marker Lines

Score along your traced line with the glass cutter, using steady, even pressure in one continuous pass. Break the piece along the score using running pliers or by hand.

For curves or notches, make relief cuts first, small straight scores that let you remove excess glass in sections before shaping the final curve. Our patterns are designed to avoid tight inside curves and narrow points, which keeps this manageable even on an early project.

Step 6: Grind the Edges

Run each cut edge along your glass grinder (or hand sanding stone if you're working without one) to smooth the rough edge from the break and true up the shape against your traced line. Grind in short, light passes rather than pressing hard in one spot.

Dry-fit each ground piece against your color mockup and its neighbors as you go, so you catch any sizing issues while the pieces are still loose and easy to adjust.

Step 7: Wash the Glass

Wash each piece in warm water with a small amount of dish soap before foiling, working the soap along the ground edges where glass dust collects. Rinse thoroughly and dry completely with a lint-free cloth. Air-drying can leave water spots and mineral deposits, so it's worth the extra minute to dry pieces by hand.

If a piece needs to sit for a while before you get to foiling, lay it flat on a dry towel rather than stacking damp pieces on top of each other.

A Few Troubleshooting Notes

I can't see the pattern lines through my glass. This usually means the glass is too dark or too textured for tracing without backlight. Switch to a light box, or fall back on the label paper or marker tracing methods instead.

My glass shifted while I was tracing. A small piece of painter's tape at one or two corners will hold the glass in place against the paper pattern without leaving residue.

My traced line looks slightly off from the original pattern. Some distortion is normal when tracing through thicker or wavy glass. Grind to your traced line rather than trying to match the paper pattern exactly once you've cut.

Between the three methods we've covered, label paper is the fastest for a first project, marker tracing gives you a reusable pattern with a built-in cutting allowance, and this trace-through method is the best fit once you're working with a light box and want to keep your paper patterns intact across multiple colors of glass. For more on choosing glass, foiling technique, and finishing your first piece, visit our Beginner Stained Glass Studio and Learn library. If you haven't picked a first project yet, the pig pattern is our most popular starting point at just six pieces.