After digging around trying to find a German WW2 Panzerzug BP44 train in OO/HO scale for my son's model railway without any success, other than a few very expensive resin kits and a 1:72 plastic kit by Armorama that is both expensive and of fairly poor cast quality from the reviews I've seen (plus would need a lot more spent on it to make get it to run on a OO/HO track) I've been toying with scratchbuilding a train from plasticard/card and using second-hand chassis' to mount the components on. To reduce the amount of "trial and error" a scratchbuild would entail I've started modelling the train in Google Sketchup, and then using the Flattery plugin can create the flat meshes to print out and glue together to make a cardstock train. Making plasticard versions would then be pretty simple using the same templates.
So far I've modelled the basic shells of the Panzerlok 57 locomotive and it's tenders using the Trojca BP44 book for reference, and printed them out with a very rough camo pattern and verified that they'll be the right size for the railway. I've also got some triple bogie frames to mount the tenders on, and I'm actively looking for a motorised chassis for the locomotive - ideally a 0-10-0 as this would match the wheel layout of the Panzerlok 57, but I'm not looking to build a historically perfect model so I'll settle for a 2-8-0 or similar layout and remove the front and/or rear bogies as necessary to fit.
I'm also veering more away from historical accuracy by adding a Panzerjager-Triebwagen 51 and a Krupp K5 Leopold railway gun to the train - I've already build the basic shells in Sketchup for these and added them to the train.
There are still another 4 different railcars to model - kommandowagen (armoured car with no guns), artilleriewagen (armoured car with turret and flakwagen on top at each end), panzertragerwagen (well wagon with Pz38t tank, although I might use a PzIII or PzIV instead), and panzerjagerwagen (flat wagon with PzIV turret), of which there should be two of each in the train either side of the locomotive, although intially I'll probably only build one of each until I build a new larger model railway for my son, as the current 7' x 4' double oval layout is going to be too small to run a fully loaded BP44. I'm also tempted to maybe add a flat wagon to be able to carry 1:76 scale models of the Tiger and King Tiger tanks.
I'll be posting updates as I go on my blog at http://www.ageofstrife.com/blog/Spack , but will try to remember to post updates in this thread here on Warseer too if anyone is interested. Click on any image above to go to the blog entry for the image and view larger versions.