Thank you both,
BeneathALeadMountain.
Oh yes , I know the feeling .... but it feels good to know you did it.
251's & 250's are among my favourite ww2 vehicles.
Here are my scifi'sed ones

6mmfan.
Card is indeed a very versatile material ( though not all is created equal ) as you can see from my numerous posts.
And the beauty is that ALL the card I used is recycled instead of being thrown away.
And for inspiration ..... With a little bit of imagination & measurement one can go from this

to this ... just go ahead & try it .... believe me once anyone goes over the hurdle of doing it the first time, then one can build almost anything ( though round parts are difficult

)
https://castrarunis.blogspot.com/2019/10/building-card-15mm-scifi-grav-vehiclr.htmlZ