I really liked Filamentry's design for this guide, particularly the fact that it's a round hole instead of having to cut a slot in the tabletop, but s/he designed it for the STUVA and I have a LACK.
I found that the basic design still let bits of wood (paperboard) fall through sometimes, so I mirrored it and threaded the two parts to sandwich the table and the rough edges, keeping the print area clean. The threads are longer than they need to be, so this can accommodate some variability in the tabletop thickness. I've found that Ikea changes parts/suppliers from time to time, so I didn't want to get overly precise there.
Note that the "Male" threaded part goes on the underside of the table. This lets you feed filament from the top without having to line it up perfectly - the guide will help you there. You can flip them if you like a challenge though :)
Designed on TinkerCAD. Started with the IKEA_hole_26x30.stl from the source project, duplicated it and applied a very coarse thread to each part (one internal, one external)
That would work in theory, but in practice that would leave parts that would be very tough to join, so I shrunk the male-threaded part by 4% to give some clearance.
Source is at