Not my cup of tea but why not look a nice kit...

Not that I'll be getting one but some have missed the point, this was not your normal artillery it was an early (1943) plan for the Sturmtiger and was based on a Tiger I with leaf spring suspension not torsion bar. However it never left the drawing board. This explains the enclosed crew compartment, as I'm sure you'd not want to be in an open crew compartment in a close quarters urban environment.

Interesting subject. I have enjoyed Amusing Hobbys kits so far.

Mäusen or Mäuse

The idea of an enclosed fighting compartment for SP Artillery was to give protection to the crew from enemy counter battery fire as the SPG scooted to the next location. If it were in an urban area, the entire unit would be in a VERY bad way if there were enemy infantry or vehicles nearby. That would be a total mis-use of this sort of weapon -- save for the occasional direct fire bunker busting role. It was a bombardment weapon -- not tasked with urban fighting where enemy infantry or AFVs could fire upon it

Roy, this weapon was to be used just like the Sturmpanzer IV and SturmTiger just check the max range of the gun - 3Km, it was to be assault artillery.

As to room inside an enclosed fighting compartment: admittedly its a larger shell, but how is this different than an M109? The shell is -undoubtedly- two-part with separate propellant charges, etc. So that makes sense. And only that....the rest is simply silly.

Built-up photos from Amusing Hobby:

That's what I thought, but then I remembered seeing an M-109 in action once: Aren't they operating with open hatches in the back? It gives much more space to work the ammo and is still quick for the Crew to get in the vehicle and change position... I don't see those kinds of hatches on the Bär... but then again, the Sturmtiger also saw the light of day and worked (for the better or worse) somehow (with I think 6-7 rounds total when fully loaded?) To the built-up pics: the tracks look a bit "off", especially in the rear section. But otherwise it looks nice (as a model kit I mean, the subject is obviously subject to debate )