After browsing countless filament guides for LACK enclosures and not finding precisely what I was after I decided to create my own.

My main goals were to produce an aesthetically pleasing guide while reducing the contact area and drag on the filament as much as possible.

I started with a simple venturi shape with wide openings top and bottom and a gentle radius to guide the filament.

I wanted the top guide to be neat since that is the side most people will see.

I also wanted the bottom guide to be nice and wide to soften the filament radius when the printer is at its uppermost Z-axis height.

I think this design achieved both.

My OpenSCAD code may not be the prettiest but I've included it here in case others wish to modify the design.

I printed a round top guide and an oblong bottom guide. It's not easy to tell from the pictures but the bottom is twice as wide as the top. This actually worked out about perfect for my needs.

To connect the top and bottom guides together I also created a simple ring coupler.

Assembly:

Measure, measure again, then drill holes through the top and bottom of the LACK table to allow the depth of the model to recess into the table housing.

With the holes drilled, use a small dab of silicone, or other glue, to attach the coupler to one of the guides.

Giving the glue a minute to set up, recheck the alignment and fit of both top and bottom guides.

Place another dab of glue on the remaining guide then press the two guides into the coupler, sandwiching the table in between.

Hold everything tightly together while the glue sets up. I turned the table upside down and placed a heavy stack of books on the underside to keep things snug while the glue cured.

Once the glue is cured, flip the table back over and you're all set.

I only put glue on the coupler itself and the result came out nice a tightly sandwiched together with the table.

Having only ever intended to print this once I didn't waste much time refining or optimizing code. The code is included but use at your own risk.

Good luck and happy printing.