How to Magnetize MDF Movement Trays for 25mm Bases

Quick answer

Magnetizing an MDF movement tray for 25mm round bases involves drilling shallow recesses, gluing rare-earth magnets, and matching polarity so your models snap into place without sliding off.

Step-by-step magnetizing guide

1. Gather your materials: You will need 3×2 mm neodymium magnets (one per model), a hand drill or pin vise with a 3 mm bit, superglue (gel works best), and a marker to track polarity. Work on a scrap piece of MDF first to test your drill depth. Common mistake: using a bit that is too large or drilling too deep can break through the tray bottom.
2. Mark magnet positions on the tray: Place your 25mm round base models on the tray and mark the center of each base position with a pencil. For the Sarissa Precision 10 x 2 Conversion Tray, you have 20 slots—mark all of them before drilling. Check that marks are evenly spaced and centered; off-center magnets can cause models to sit crooked.
3. Drill shallow recesses: Using a 3 mm bit, drill a 1.5 mm deep hole at each mark. Go slowly to avoid splintering the MDF. A depth stop (or tape on the bit) helps keep holes consistent. Common mistake: drilling too deep weakens the tray or exposes the magnet on the underside.
4. Glue magnets into the recesses: Apply a tiny drop of superglue into each hole, then press a magnet in with the same polarity facing up for all slots. Use a spare magnet to check that your models' magnets attract rather than repel. If you glue a magnet with the wrong polarity, you will have to pry it out—so test polarity before the glue sets.
5. Let the glue cure and test fit: Wait 15–20 minutes for the glue to fully cure. Then snap your 25mm round base models onto the tray. They should hold firmly but lift off easily when you pull straight up. If a model wobbles, the magnet may be too shallow or too deep—remove it and adjust the hole depth.

Product used in this guide

• 10 x 2 Conversion Tray for 25mm Round Bases: MDF conversion tray consisting of MDF upper frame and lower base. Select the height of frame required to match your bases. The removable lower base gives you a flat surface to drill into for magnets, while the upper frame keeps your models aligned in ranked formation.