I'd be careful with the idea of the interlocking fingers having a good friction fit, especially if it's to be assembled and disassembled. Regarding fit, each part needs to have a 'perfect' size that will allow the whole to work - anything outside of that will either result in slop or be a very tight fit such that assembly will be difficult in the first place. All components have tolerances, and the sizing needs to be spot on to get friction. Even a handful of microns out can change it from friction to sliding, or to some small amount of damage or surface wear if tight. Aside from that, no matter how snug it is to begin with, there will be wear during assembly and disassembly that will eventually turn the fit into a sliding one in any case, at which point, there is a risk of slop (once you have slop, wear reduces markedly).
Whether or not slop is an issue is down to the size of the gaps between the surfaces, and in what direction the slop might be a concern. With a sliding fit, the back could move away from the base, causing the film plane to be in an unpredictable position. Similar thing with unintended swing. There is also a risk of tilt, which would feel like the rear standard wobbling at the top when in use. The movements might be slight and not have an adverse effect on the images, but the user's perception of it might be that it's not as well made as it could be.
For what it's worth, in my line of work (precision mechanical design), I would never use a simple friction fit for something that's going to be assembled and disassembled as part of its normal usage. Always a sliding fit that's secured with some mechanical thing, like screws, a flexible clip or sprung latch/catch/pin. The only time I'd use a friction fit is for something that's captive and not normally removed - like a dowel in one part that has a sliding fit in the mating part (only used for precision alignment of the two parts, not for holding them together - the friction fit at one end of the dowel is to stop it falling out, and slightly improves accuracy). With that, the dowel needs a pin punch and a hammer to take it out of the part it's captive in, which would be rare and might need something like Loctite to get a dowel back in that that will stay captive (a bit of inny-outy of a press-fit captive dowel can turn the fit into a sliding one).
I would be doubly cautious of trying to make a sliding fit from acrylic. As engineering plastics go, it's not the greatest. It's not particularly hard wearing and can be prone to impact damage at the edges. I virtually never use it, and even then, it's for things like safety screens in machine housings rather than a mechanical component. That said, the laminate thicknesses you're using don't seem too bad and I think the joint itself would be robust enough. However, I would definitely be looking at some sort of mechanical method to hold the parts together. I'd maybe consider something along the lines of captive threaded studs pointing down from the bottom edge of the rear standard, which go into open-ended slots in the base, the two clamped together using female thumbscrews (which can be left on the studs). I'd also maybe buffer the interface between the thumbscrews and the acrylic base with something like nylon washers to reduce risk of crush damage to the acrylic. (Lots of ways to do this, but that strikes me as easy to make - two tapped holes in the upright and glue in two studs - and still quick to assemble in the field.)
