Loudspeaker driver surrounds DIY

Step 3 Plaster part of mould part 2

The MDF part is fenced with wide packaging tape on the outer edge, the central hole taped over, and the entire surface smeared with vaseline with no lumps or ridges. Moulding plaster is poured in (creamy texture to about 20 mm thick) tapped to encourage bubbles to surface, and allowed to set on a level surface, so it's not moist and white in colour, possibly over a day or 2 to be sure, the latter part of drying out can be with the tape removed . Mark where the 2 parts are aligned. Gently tap the mdf all round to release the 2 parts. Smooth / fill any air bubbles Can also be given a thin coat of gloss acrylic.