Ladder feet
thingiverse
Update: I've widened the bottoms, added some texture and made a few other little improvements. I've left the smooth bottomed version there for anyone that wants it but I'd recommend the ladder_feet_grip version. After the plastic feet on my ladder disintegrated I created these as replacements. Printed out of TPU, they fit perfectly over the 48x18mm aluminium legs. I can't tell you the brand of ladder, it was bought from Bunnings in Australia about 15 years ago if that helps. I've included the blender file for anyone who wants to tweak it.
With this file you will be able to print Ladder feet with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Ladder feet.