There are many ways to make face plates and other such items for use on the lathe, you can cut a spigot or recess to fit on your chuck. You can mount it on a screw chuck or glue block, all these work as a one off but for a piece you will use often or for heavy or awkward shapes you need something a bit sturdier.
You can buy nuts of the correct size for your spindle and glue them into a recess in a piece of wood but I have found this a bit tricky in the past to get everything running smooth and getting a good bond between the nut and the wood.
I now use a tap to cut a thread in a piece of wood so it fits directly on to the spindle, for this I use a Beall Spindle tap HERE. I brought this one because it was the cheapest I could find at the time for my Hegner which has a M33 x 3.5 thread but you can get them elsewhere.
The best wood to use is a close, closed grain wood such as box or holly, you can use other woods but the coarser the grain the more likely the thread is to crumble. To over come this once you have cut the thread flood it with thin superglue and leave to dry then run the tap through the thread again to clear out the excess glue. You can also put a thread directly into ply wood using this method, but I prefer threading a boss and then gluing and screwing a piece of ply onto that.
Below is how I cut a thread using the tap.
The first thing to do is measure your spindle to get the correct sizes, the measurements I give here are for my Hegner. You need the overall size from the back of the register to the front of the spindle A=30mm. The depth of the register B=11mm and the diameter of the register which is not marked on the photo but is 34mm