Mighty Max Carts - improvements to cargo end walls

The Mighty Max Cart is a sturdy dolly to move heavy things, but the Cargo End Walls are poorly designed. When used without a tub holding the four corners in place, the bungeed end pieces pull inward and eventually pop off.

I designed a mostly non-destructive, easily removable system of lock and buttress pieces that can be 3D printed with PETG.

You need FOUR of each:

• printed spacer pieces
• printed brackets
• 1/4" x 20 bolts, between 1/2 to 3/4 inch length, preferably with a wide screw head
• 1/4" x 20 nuts
• drill with 1/4" drill bit
• Phillips screwdriver
• (optional) washer
• (optional) removable thread locker (aka. Loctite)

Print notes:

• I printed with the Spacers with a 0.6 nozzle and the Brackets with a 0.8 nozzle. You can use any nozzle down to a 0.4.
• Increased Perimeters to 3
• Switched Infill to 25% Rectilinear
• 0.3mm layer height is fine.
• This pairs well with the slightly modified Bobstro Support Settings that work with all nozzle sizes (see last photo)
• Print the Spacer with the screw hole facing up and supports on the build plate.
• Print the Brackets with the beveled edge facing up and supports on the build plate.
• I used Printed Solid's Jessie PETG, but any brand should work well.

Assembly instructions:

1. Insert End Walls onto cart. Flip cart on its side or upside down.
2. Mark where to drill the screw holes by removing the wheels and dotting with paint pen or scratching the plastic with an awl.
3. Remove End Walls and drill 4 holes. I recommend drilling small pilot holes first before using the 1/4" drill bit.
4. Print one or more Spacers.
5. Insert nut into spacer and push into the bottom of an End Wall foot.
6. Check alignment. Three of my Spacers were aligned perfectly. You can insert an Allen key or small screwdriver into the notches and screw hole to pull out the spacer if needed. Please work carefully; I am not responsible if you damage your End Walls.
7. I drilled the fourth hole a little too low. I could have enlarged the drilled hole, but I chose to adjust my 3D model and print a one-off instead. I included the STEP file for the spacer in case you want to do the same.
8. Repeat Steps 4-6 for remaining feet.
9. Once the four spacers are installed, print the four Brackets. Honestly, these may be unnecessary. I designed them as the original fixes to my problem with the End Walls, which didn't work. I figured they might add additional buttressing so I included them here.
10. Push in the Brackets. You can insert a small screwdriver into the hole to pull out the bracket if needed.
11. Insert End Walls onto cart. Flip cart on its side or upside down.
12. (Optional) Add washer to bolt.
13. (Optional) Apply a small drop of thread locker on the bolt. Use sparingly and try to avoid contact with any plastic.
14. Screw in bolt. Repeat for remaining three feet. You may need to remove the wheels or use a right-angle screwdriver for two of the bolts.