The best plywood and MDF for laser cutting
The short answer: for press-fit boxes and decor, use 1/8" (3 mm) Baltic birch or basswood plywood. Use MDF for painted pieces and for practice. Measure the real thickness of whatever you buy, because the joints are calculated from it.
The materials, one by one
- Baltic birch plywood: many thin plies and no voids, so it cuts evenly and stays flat. It is the best all-round choice for boxes and lamps. The edge is a pale stripe pattern that many people like.
- Basswood plywood: soft, light and very easy to cut, and it takes stain evenly. It is the usual sheet in laser shops for ornaments and small decor. It is less stiff than birch.
- MDF: uniform and cheap, with no grain. It cuts cleanly but leaves a dark edge and a lot of dust, and it swells in water. Paint it, and do not use it outdoors.
- Craft plywood from a big-box store: it often has voids and glue that cuts unevenly. Fine for tests, risky for a gift.
Thickness: 1/8" is the sweet spot
The plans in this site use 1/8" (3 mm) sheets as the starting point. It cuts in one pass on a CO2 laser of 40 W and above and gives rigid joints. Thinner sheet bends, thicker sheet needs several passes and leaves a tapered edge. If your laser is a diode laser of 10 W or less, expect to cut basswood in several passes and to go slower.
What to check before you buy
- Measure the thickness with calipers in several places. Labeled 1/8" can be anywhere from 2.8 to 3.2 mm.
- Look along the edge for gaps between plies: they burn and leave weak spots.
- Lay the sheet on a flat table: a bowed sheet changes the focus and the cut depth.
- Choose sheets that fit your bed. The default sheet in the plans is 24 × 12 in; you can change it in the settings.
Cleaning the edge
Laser cutting leaves soot on the face and edge. Cover the sheet with masking tape before you cut, or wipe the soot afterwards with a damp cloth and sand lightly with 220 grit. Seal and finish only after the parts are dry-fitted.
Frequently asked questions
Can I use thicker plywood than 1/8"?
Yes, but enter the real thickness, and expect more passes and a slightly tapered edge. Most press-fit plans work best at 1/8" (3 mm).
Is it safe to laser cut MDF?
It cuts well, but it produces more smoke and dust than plywood. Use good extraction and ventilation.
Why is my plywood cutting unevenly?
Voids or glue pockets inside the sheet. Baltic birch has no voids, which is why it is the usual choice for joints.