Perfect sorter and priced for what you get!
The Product: This sorter works excellently. When using, sorting twice seems to be ideal. When you place a lot of Lego in the top, some longer pieces will align themselves to fall through to the next layer. Doing an initial rough sort allows you to selectively re-sort sizes to keep the longer pieces on the layer above (as they'll lie flat and not fall through the holes). While with casters, you can move it around back and forth, side to side, I've found that for a first pre-sort, picking the whole thing up and moving it up and down (carefully) and around is more effective (but my hands aren't small, so I can grip the layers well from the sides). I'm contemplating getting a small shaker motor to attach, as that may be more effective than shaking by hand. And, instead of the casters, you can put adhesive felt on the bottom (like you put under furniture). That will allow shaking it by pushing it back and forth, side to side, on a flat surface (but maybe not your expensive furniture).
Assembly: Some woodworking knowledge is likely helpful. I sanded the expected contact points (the accessible ones, not inside holes) and brushed on wood glue (including inside the receiving holes). They mention the benefit of clamping, but I used a pin nailer (23 gauge) to tack the joints together with the small nails. A few of the nails went astray and popped out the face of the wood, but I pulled them out. I then wiped away any glue squeezeout with a wet cloth.
The Cost: As to the value of the sorter, the baltic birch itself is worth around $50-60. I don't know how long they take on the laser cutter, but that has a cost as well. There's also the original design time to create and optimize the files for the cutting (don't underestimate this as it takes some time for aspects like getting tabs tight but not too tight). Then, packing and (free) shipping. Lastly, profit is needed to keep a company in business for them to offer us their next cool products.
The Value: $189.99 with free shipping is reasonable for what you get. It's not cheap, but you're also getting a high-quality and very useful product. If I had a laser cutter, I would be quite pleased with myself if I had come up with this design!
Improvement: The system is good! The only idea I can think of is an option for 2-3 more sieve layers, perhaps. Otherwise, the design is optimized for what it is: a flat-packed, tab-based, user-assembled, real-wood product.
