I have recently decided to undertake a new project of building large scale model of a Mark IV tank, by machining all parts myself manually and with some CNC parts. I have been a hobbyist machinist for some years now and have the skills to do it, though I am lacking any real reference material, only the exterior hull blue prints from the Haynes great war tank owners workshop manual. I would appropriate any help concerning the design and dimensions of the mark IV as I am relatively new to it all.
Bovington's plan service may be able to provide more of the material you need. It is some time since I contacted the museum, but they used to be very helpful.
The plans for the full-size MkIV Female replica built recently in the UK mostly came from Bovington, with some help from a fella in Germany who had produced digitised plans. Bovington also of course have one of the very few surviving MkIVs, the only one which is pretty much complete and the only one still functional. So you have a 1:1 reference source there. Just beware that there are a couple of oddities from its refurbishment and return to service in 1940, such as Hotchkiss ball mounts instead of Lewis.
The "fella in Germany" contributes to this Forum. I shall let him introduce himself if he wishes to, but to say he gave "some help" is to under-estimate his contribution to our understanding of the Mark IV by a significant margin!
I am the one who supplied the CAD files for the programme with Guy Martin. The CAD model was based partially on the blueprints from Bovington. As large portions of the tank were not covered by the available data, I also used hundreds of photographs and measurements to make it as accurate as possible. I am extremely grateful for the help I received from Gwyn, without whom this would not have been possible.
Detailed drawings and the findings we made during this research will hopefully be published in printed form, but this plan is still at its early stages.
If you need drawings now, I recommend the Haynes Owner's Workshop Manual and the plans from the archives at Bovington.