These ThrottleCaddys available in many sizes with two designed specifically for Digitrax, one short for Engineer's Throttles and the XT for the DT40XX series throttles. They are available on eBay from seller briank01510. They are laser cut masonite and come in a kit. Glue and paint to match your facia. Device allows FULL access to ALL buttons without removing device from the pocket.
I stumbled on to them, here is a link
and these are the words in the 'Subject'
Cab Holder Fits Digitrax cabs,Cab Cubby tm UT DT, Easy to assemble kit,HO,N,G