You mentioned this
The Char St. Chamond was not a successful design, *however* the garish camouflage patterns, the full-sized M1897 75mm gun, and the fact that this lumbering brute along with the Schneider CA1 will convert beautifully into WH40K Ork AFVs makes them real winners if they were available in hard plastic at an affordable price.
Who makes a hard plastic Schneider CA1?
that's the thing; AFAIK *no one* does! I've seen some resin and multimedia kits, but they tend to be fairly expensive to say the least.
For my own part, a 1/56 scale plastic Schneider CA1 in a simplified construction format for wargamers would justify adding quite a few to my collection, as the CA1 in particular was used during WW1 by the French Army as you know, but the story of the CA1 in combat didn't end in 1918!
No sooner had the shooting died down in Western Europe, but by the 1920s the Rif War was in full swing in Morocco, and Spain was struggling to hold onto her colony in Morocco. To bolster their sagging fortunes against the Riffian insurgents, the Spanish Army purchased a number of Char Legere Renault FT17s, *and* a number of Schneider CA1s to provide heavy fire support.
The Spanish CA1s fought to the end of the Rif War IIRC, but their story didn't just end there. The Spanish Army kept a small number of CA1s on inventory, and sure enough when the Spanish Civil War broke out in the 1930s, out came the CA1s again, being used by the government loyalist militia in the street fighting in Barcelona!
So for yours truly, I'd start by procuring some CA1s for my Great War French wargame army, probably four total for a full battery, however given that painting up early French armour from the Great War is a guilty pleasure of mine, I may eventually wind up with a full groupe of four batteries.
Now we move to scenic Morocco! As i have long wanted an excuse to venture into the Rif War, and Askari Miniatures already makes a very nice line of 28mm Rif War Spanish and Riffians, I would simply have to add a pair of CA1s in Spanish Army colors as well.
Finally, being the SCW nut that I am, I would not be able to resist doing up at least one CA1 in the colors of the particular Spanish Communist Youth Movement militia that deployed one of these metal dinosaurs during the street fighting in Barcelona:
Now of course, the CA1 also would work for Pulp Fiction as well (evil Chinese warlord villain has plans to become the next Son of Heaven, and he's got a new toy that will help him in his diabolical plan, and it's up to our heroes to stop him, etc.). A CA1 in speculative colors for a Chinese warlord from the 1920s? Absolutely.
Sci-fi? Well, the CA1 is IMHO just begging to join the ranks of any WH40K Space Ork mob, just add spikes, assorted Ork weapons, and an appropriate Orky paint job.