The best materials to engrave with a diode laser are those that are non-flammable and have a high absorption rate for the laser's wavelength. Some good materials to engrave with a diode laser include:

• Wood
• Acrylic
• Leather
• Paper
• Fabric
• Glass
• Ceramics

It is important to note that not all materials are created equal when it comes to laser engraving. Some materials will engrave more easily than others, and some materials may require special settings or techniques to achieve the desired results. It is always best to test a small area of the material before engraving a large project to ensure that you get the results you want.

Here are some tips for engraving with a diode laser:

• Use a high-quality laser engraver. A good laser engraver will have a powerful laser and a stable platform.
• Use the correct settings for the material you are engraving. The settings will vary depending on the material, the thickness of the material, and the desired results.
• Wear safety goggles when engraving. Lasers can be dangerous, so it is important to protect your eyes.
• Work in a well-ventilated area. Lasers can produce fumes, so it is important to work in a place where the fumes can dissipate.
• Be patient. Laser engraving can be a slow process, so be patient and take your time.

With a little practice, you will be able to engrave beautiful and intricate designs on a variety of materials with your diode laser.