A laser cutter removes material using heat. On wood, plywood and MDF, this makes the cut edge darker than the sheet surface. This edge is characteristic of the process and is particularly visible on light woods.
Different sheets produce different edges
Species, adhesive layers, thickness and the shape of the part affect the result. A cut through thin poplar plywood looks different from one through thick MDF. Do not expect identical colours between materials.
Make the edge part of the design
On a construction kit, display or separate letter, the contrast between a light face and dark edge can work well. If you primarily want to show the face, arrange the construction so the joint or edge is concealed.
If every side needs the same colour, include edge finishing in your plan. Internal corners and small openings are harder to sand or paint than straight outside edges.
Surface residue and the cut edge are different
The face near a cut may show signs of processing as well. Protective film can help protect visible surfaces on suitable materials. Availability differs by sheet; read about protective film and adhesive backing.
Inspect an actual cut part
A sample gives an impression of the surface and colour. For a particular joint, thick edge or fine pattern, a prototype is more useful. It shows the material as used in your design.
Compare wood-based sheet materials with the final visible edges in mind.