I have created a blocker to stop kids and dog toys, balls, etc. from going under the sofa and other furniture. Each of the 100mm length blockers requires approx. 20g of plastic which amounts to cheaper than similar blockers if you are buying something off the shelf instead. These are for spaces that require 70mm of coverage but I can modify the width if needed. Can apply some double-sided tape to the flat part and stick it either to the bottom of your furniture like I've done in the picture, or to the floor directly. I also applied some foam to reduce the risk of running your toes into the gap and scraping some skin off.

Print settings - 10% infill, 2 walls, 3 layers on the top and bottom. All in all, these can be printed around 1 hr per blocker on medium speeds on my old Ender 3 pro.