The IKEA LOGGA shoe rack has about 60 mm clearance under it which is too low for most robotic vacuum cleaners.
I made these leg extenders, which replaces the original feet, to gain enough clearance for the Neato XV series.
The extenders fits inside the 19.5 mm pipe and increases the clearance to about 105 mm, which is enough for most robotic vacuum cleaners.

The design was made for printing in ABS.
For other plastics you might have to change the scale slightly.
I printed using 1.2 mm walls and 30% infill.

This design can probably work on other furniture with similar design.
Scaling it in all dimensions, in X-Y only or in Z only should make it possible to adapt it to different height requirements and different tube diameters.

Don't put this on heavy furniture, it might affect the stability of the furniture or fail under heavy load, creating dangerous situations!