Use a fine, high-contrast repeating pattern whose spacing gets close to the camera sensor’s pixel pitch. The most reliable subjects are printed moiré test charts (especially concentric circles or fine mesh), tightly woven fabric, wire mesh, or other dense repeating textures. A brick wall can also work well if you shoot it at an angle so the apparent pattern size changes across the frame.

For repeatability:

• Fill much of the frame with the pattern.
• Change distance or focal length so the pattern frequency on the sensor sweeps through the critical range.
• Shoot slightly off-axis or with perspective so spacing varies across the image.
• Use the sharpest focus and lens/aperture combination you can; sharper capture tends to make moiré easier to trigger.

A non-AA camera should generally show moiré more readily, while the AA-filtered version should suppress or reduce it. Concentric-circle charts are especially useful because they naturally pass through many spatial frequencies in one frame, making it easier to see where moiré starts.