Greetings,
regarding using good quality plywood for tops, we have been using recycled
plastic for tops for some years now without noticing any negative
attributes. It comes in 4 x 8 sheets in various thicknesses, cuts like ply,
and nails or screws like ply. Doesn't need any painting and my well be
indestructible. I use migratory lids and during the first few years we
checked its compatibility with the bees and noticed no obvious negative
effects, they wax and propolis it just as wood.
Peter

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