You're close, but some of your parameters have weird units. Lower your first layer thickness to 0.25mm; subsequent layers should be 0.25mm as well. Your slicer appears to want the top, bottom, and perimeter layers in mm, not layer numbers. If I'm reading your screen right, you've set it for 12mm top and bottom layers. You want 12 layers at 0.25mm each = 3mm each, top and bottom. Ditto for your shell thickness, looks like it's specced in mm. Here, you want 8 perimeter layers. Converting to mm depends on how your nozzles are set, most have a line thickness equal to about 110% of your nozzle width. For a 0.4mm nozzle, 0.45mm lines are standard. 8 of these lines is 3.6mm thick. If you're specing perimeters in mm, you'll want abou 3.5mm here. 200C print temperature is a bit low, depending on what PLA you use. I've printed over 10 full sets now, with Prusament Galaxy Black, at 215 C (60 C Bed). Print a single part at a time, that way you can debug and test fit w/o killing a lot of filament. I'd start with the slider. That's the hardest and most critical part, and getting it to fit properly in the extrusion will tell you alot about how your built your printer, and whether you have any built-in "skew" (aka, it's not square).