Andy, The material of the washer is not critical. You can obtain the correct height by purchasing brass shim stock at a hobby store.
The packs come with a variety of thickness and can be cut with stainless steel scissors. For the hole in the center, sandwich the shim stock between 2 pieces of wood (this minimizes the likelihood of a ragged hole)and drill the spindle hole.
The tighter you clamp the record to the platter, the better (energy from the stylus is transferred from the vinyl to the platter rather than reverberating back to the stylus).
The packs come with a variety of thickness and can be cut with stainless steel scissors. For the hole in the center, sandwich the shim stock between 2 pieces of wood (this minimizes the likelihood of a ragged hole)and drill the spindle hole.
The tighter you clamp the record to the platter, the better (energy from the stylus is transferred from the vinyl to the platter rather than reverberating back to the stylus).