1/4" remix of the 3/16" version. The only change is the wheel. I designed it from scratch and I am including the STEP file to mess with if you want. I first designed and printed this mid 2023, but it took me a while to upload. The wheels mesh together pretty tightly, so you might want to print a set of four to test inside the brackets before committing. You could also add a tiny bit of horizontal expansion compensation if you are worried, but as is they should work fine. May just require a bit of use to loosen up. Having clean seams and avoiding blobs will help the line roll freely. If anyone needs something changed or has questions please feel free to comment.

Works well! A bit more of a task to assemble than I expected, mostly because of the washers. I actually printed all four brackets in different orientations just as a fun test. Surprisingly, it even printed perfectly on a single line of the sharp corner just with a small raft. No issues printing in any orientation, but I suggest putting the side with the chamfered hole for the bolt head down on the bed. This creates rings that won't crack as easily when tightening the bolts. I used this orientation for all four sides on my 1/4" remix. Printing thick layers should work fine.

Highly recommend a hard and durable PLA like Inland PLA+ for this. My print using more matte and chalky Inland PLA Pro was not nearly as nice and cracked more easily. I'm sure other materials can work well. Layer adhesion is key. I pressed my wheels onto the bearings using a bench vice and some wood. No wheels cracked initially, but some have after use and sitting in the cold garage. So you may want to print these with a very slight hole compensation factor. Some test printing and fitting is always a good idea.

I made threads by just screwing the bolts in or by heating them then screwing them in. Using heat reduces the chance of cracking, but too much heat or applied torque and you will ruin the threads. I can see an argument for printing the holes that need to be threaded on the bed too though. I had no cracking with PLA+ and one outside hole cracked with PLA Pro. If the part cracks after forming threads, you can try super gluing the crack and clamping it or even melting it back together. You can also try a tap instead.

While there are cheaper options for line straighteners now than when this was originally created, it's still a fun project and can save some cash. I made a video about the assembly and use here: https://www.tiktok.com/@802garage/video/7277736811890347307

Here are some affiliate links to the bolts I used and some of the cheapest bearing deals I can find since you don't exactly need the best quality bearings for this tool.
https://amzn.to/42X2VP6 - Fullerkreg M8-1.25x20mm Stainless Hex Drive 25 Pack - $8.99 (Has letters, slightly better quality.)
https://amzn.to/48tyMrO - MewuDecor M8-1.25x20mm Stainless Hex Drive 25 Pack - $9.49 (No letters, acceptable quality.)
https://amzn.to/42T8uy9 - Tonmp 608ZZ Metal Shielded Bearings 30 Pack - $6.99
https://amzn.to/3wzEZ8j - Tonmp 608ZZ Metal Shielded Bearings 50 Pack - $11.79
https://amzn.to/4bVOmPR - Homepa 608RS Rubber Sealed Bearings 22 Pack - $6.99
https://amzn.to/3IjyJnG - Tondiamo 608RS Rubber Sealed Bearings 30 Pack - $7.99

I'm interested in designing a version that uses print in place bearings built into the wheels and no washers. Would make it a lot cheaper and easier to assemble, though harder to print. We'll see if I ever get around to it!