Mornin' Reg.
One of the easiest ways is to turn a nice piece of timber to a shape and size to the amount of pens you want to hold, with a gently rounded top. Mark the centre of the top with a pencil then concentric rings moving out from the centre. How many you can fit in depends on the size of wood. Mark equal spaces around the rings, then take the piece to the pillar drill and drill holes at all the marks and the centre hole.
If you drill the outer holes deep and the inner rings shallower as you move to the centre you can get at all the pens/pencils as they are at different levels.
Even fancier, tilt the pillar drill table ever so slightly for each ring with the centre hole vertical and the pens will splay out a little.
The actual size and external shape can be anything that fits the amount of pens. My general size to start is approx. 3 1/2" dia. x 5" long, which also includes the spigot for the chuck. Finished size is around max 4 1/2" high x 3" dia. I don't usually measure anything just eyeball the sizes, but set the pillar drill depth stop for each penciled ring so they are equal.
If you haven't got a pillar drill you can use a piece of timber in the banjo in place of the tool rest with a hole at centre height same size as the drill you intend using. Just set up the wood guide at the angle and depth you want and away you go.
Apologies for being so long winded, but have made a few of these using the above methods and they work OK.