Yes the Ebony Star is OS. A bloke called Dean Sala has it precut. There is a link on the Stellafane website.
With the focuser board, that is an issue that I am still wrestling with. That is why I have made 4 upper rings out of cheaper ply wood to experiment with before the final build using marine ply.
My plan was to use dowells and glue and add a couple of metal 90 braces. But plans are always tentative until final build!!
Or I discover I have no idea and start again.
Malcolm