00 Scale Northumbrian Loco Scratch Aid (Version 2)

Commissioned as a variant of my other Liverpool & Manchester Railway ‘Northumbrian’ class locomotive (separately available), this model differs in featuring a shorter ‘keyhole’ smokebox and shorter frames with bufferbeam.  Combined with the 00 scale Northumbrian tender (separately available), this scratch aid enables an unpowered free-rolling model engine that can be ‘motorised’ by coupling to a power source such as: https://www.shapeways.com/product/F9H5PPBEC/00-scale-open-truck-motorised 

IMPORTANT: while most models available here have been pre-tested and known to work, this scratch-aid has not been printed/tested by myself, so while the measurements appear correct it is considered strictly experimental.   

(Note: various materials are provided, however, WSF and BSF will require more preparation for smooth painting that FUD and FED.) 

The following additional parts need to be sourced separately to complete (web links given as examples only): 
Driving wheels (20mm diameter including flange; c.19mm without)
Trailing wheels (12mm diameter including flange; c.11mm without)
      (These all appear on the current Alan Gibson catalogue)
Slide bars - holes for these are marked and can be made of wire with a system like the N Gauge variant (see video below)
Coupling rods (various lengths are available via Alan Gibson which could be adjusted or these can be scratchbuilt to suit).  
Loco-tender coupling 

Optional additional details to add (at the builder's discretion):
Crew