As well as some axles and 3' 10" wheels, Alan Gibson Workshop does some at 3' 11" which scales at 15.6mm, also smaller ones at 3' 8" which scale at 14.6mm, the photographed example of this tender is the original build that has since been shortened in design in its overal length after finding superiour scale drawings, the original model also has 3' 6" wheels which scales at 14mm's.
 
They will need a chassis to complete.  4mm one's are available for £12 each although they are only a stop-gap to producing something more robust.  They work fine but in resin are a bit brittle so care is needed when threading wheels on to axles through the chassis etc, small 2mm spacing washers are a good idea too depending how much  lateral 'give' you want the wheelsets to have.  The chassis need a little filing before they fit well due to the MSLA printing process is all.
 
The completed photographs of the Furness example are of the now unavailable Shapeways WSF/WNVP material which is a bit grainy in texture.   SCC MSLA resin prints are a lot smoother by default.
 
This tender is also for the Cambrian Railway Class 61.   There are 'tear drop' shaped cut outs in the frames and parts to fit here, fit them for Furness Class K2 / 21 and fill/file smooth and leave vacant for the 61.