Shadow box material guide: cardstock, spacers and frames

A layered papercut depends on more than the SVG. Paper stiffness affects fragile details, the gap between sheets controls the shadows, and the adhesive determines whether the finished stack stays flat.

What you need

• Cardstock for every structural layer
• Extra cardstock for decals and test cuts
• Foam tape, foam pads or another consistent spacer
• Paper-safe adhesive
• A deep frame or shadow box
• A clean cutting mat and suitable blade
• Tweezers for small decals
• A ruler or caliper for checking the finished depth

1. Choose the cardstock

Start with cardstock around 80–100 lb cover, approximately 216–270 gsm, then test the exact paper before cutting the complete project.

This range is usually stiff enough to keep a full sheet flat while remaining practical for detailed machine cutting. Heavier cardstock can make the finished piece more rigid, but tight curves and narrow strips become harder to cut cleanly.

Why pounds and gsm do not always match

Gsm measures the mass of one square meter of paper. Pound ratings depend on the paper category and the size of the manufacturer's basis sheet. Two papers with the same pound label may not have the same thickness or stiffness. Gsm is usually more useful when comparing brands, but a test cut matters more than either label.

2. Check more than the paper weight

3. Plan the paper colors

Use the assembly guide to match paper colors to layer numbers, then check neighboring colors together under the light where the finished work will be displayed.

The number of structural layers is not always the number of colors. Several layers may use the same cardstock, and decals may need extra pieces from a color already used elsewhere.

1. Lay the cardstock colors together in layer order.
2. Check whether neighboring colors are different enough to reveal the cut boundaries.
3. Photograph or label the stack so the order is not lost.
4. Keep spare paper for test cuts and replacement layers.

Screen colors are only a guide. A hexadecimal color cannot account for paper texture, room lighting or the difference between a display and a physical sheet.

Use contrast to preserve depth

If two neighboring colors are almost identical, the depth between them may disappear. Change one paper color, increase the gap between those layers or use stronger directional lighting.

4. Choose the space between layers

Start with a 3–4 mm gap for balanced depth, then use the 3D preview and the available frame depth to decide whether the project needs tighter or wider spacing.

Layer gap and paper thickness in the KerfPress 3D view change the preview only. They do not change the SVG or PNG cutting outlines.

5. Calculate the finished depth

Add the thickness of all cardstock, the spacers between structural layers, the backing and enough clearance to close the frame without compressing the artwork.

For example, eight layers with 3 mm gaps need approximately 21 mm for the gaps alone: seven gaps multiplied by 3 mm. Add the combined cardstock thickness, backing and a little clearance.

Measure the actual spacer rather than trusting its product name. Foam sold as 3 mm may compress once the frame is closed.

6. Choose spacers

7. Support the sheets evenly

A spacer only in the four corners may leave a large sheet sagging in the center. Add hidden support around the outside border, behind broad paper areas, near narrow connections and under islands before trimming their bridges.

Check the front of the artwork before pressing adhesive firmly. A support placed too close to an opening can cast an unwanted rectangular shadow.

8. Choose an adhesive

Test the adhesive on a scrap of the same cardstock. Check for staining, shine, warping and weak adhesion after it dries.

9. Prepare the cut layers

1. Turn the mat face down.
2. Peel the mat away from the cardstock.
3. Remove waste from large areas before fine details.
4. Check narrow strips, islands and bridges.
5. Place the finished sheet back into the numbered stack.
6. Keep decals in a separate labeled container.

If a sheet curls, place it under a clean flat weight before assembly. Do not press fragile raised details directly.

10. Dry-stack the project

Place every structural layer and spacer in order without adhesive, check the outside alignment and confirm that the complete stack fits inside the frame.

L01 is the deepest structural layer at the back. Higher numbers move toward the front, and the highest-numbered layer is the outermost sheet.

1. Check that every outside border aligns.
2. Confirm that each opening reveals the intended color.
3. Test the planned spacer thickness.
4. Place the complete stack inside the frame without forcing it.

11. Assemble and support the layers

Add hidden support around the border and behind broad paper areas, attach decals to their target layers and support islands before trimming bridges.

When building flat on a table, begin with L01 and add progressively higher layer numbers. When loading loose finished sheets into a deep frame, insert the highest-numbered front layer first, then continue downward until L01.

Attach decals

A decal is cut separately and glued onto the surface of a structural layer. Use the decal placement guide and attach it before that area becomes difficult to reach. Tweezers and a fine applicator help with small pieces.

Finish bridges

A bridge keeps an otherwise loose piece connected during cutting and positioning. Position the structural layer, support the island underneath with a spacer of the correct height, glue it in place and let the adhesive secure it before trimming the bridge.

12. Choose the frame

A suitable frame needs an opening large enough for the finished width and height, enough internal depth for the sheets and spacers, and clearance so the front layer is not pressed against the glazing.

A frame sold by its outside dimensions may have a smaller visible opening. Measure the internal opening and usable depth directly. If the border will sit behind a frame lip or mat board, make sure important artwork does not enter the hidden area.

Before final assembly

• Every structural layer has been cut at the same size.
• The sheets are in the correct numbered order.
• The paper colors match the assembly guide.
• The dry stack fits the frame opening.
• The total depth fits without compression.
• Spacers are hidden and use a consistent height.
• Islands are supported before bridges are trimmed.
• Decals are attached to the correct structural layers.

Learn how islands and bridges work

Review the complete shadow box process