Longworth Chuck well worth making, there is loads of info around the net, there is also a pdf on my site for download.
I have a couple of these the one you see and a 6 way that is made complete with acrylic, the one you see is made with mdf that is steeped in super glue, the back is thread to go straight to the shaft of my lathe, the wood for the thread is nade of beach.
The 6 way is better i find than the 4 way, must go get that back from the wifes father, can i use yours to copy, 3 months he's had it know, family a.
Reveres bowls and boxes do the bottoms its a great bit of kit.
The 2 ply spanners are for measuring the spigot ends for my chuck saves messing around setting up calipers whatever, have a pair for each of the chuck jaws i have, one for the small opening and for the larges, just saves time and its just a bit of 3mm ply.
And a simple handle on a drill bit, take out the centre of the turning, genrally on my small box turnings.