Kids Ride-On Balance Bike — Easy Print & Assembly

A push bike that rolls on four empty spools, fully 3D printed with zero hardware.

The basics:

• Snap-together assembly: no hardware or tools required
• Wheels: 4× empty filament spools
• Rider: ages Toddler to 6, up to ~60 lb
• Sized for P1S and up: segmented to fit with no supports

Never printed anything this big? Most people haven't - plenty of us never get past desk trinkets, and that's exactly who I built this for. The part count might look intimidating, but for a vehicle a kid actually rides, it's remarkably lean. It took a fair bit of design and testing by my kids to get it there. Assembly is styled like your favorite brick system: a big illustrated, step-by-step PDF that walks you through it part by part. If you can print and follow pictures, you can build this.

Beyond filament, you need nothing. No bolts, no bearings, no glue, no trip to the hardware store. Every joint snaps or threads together with printed parts. The only "extra" item is plastic-safe lubricant (not WD-40, a non-spray silicone or white lithium grease, such as "Plastic Gear Grease") which makes steering significantly easier. It can be added after assembly or skipped entirely and the bike still works, your kid just has to stand up to change the steering angle.

It's a system, not just a bike. This is the Panda kit of the Spoolster system. I built the blacked-out Nightfall kit first, my kid took one look and decided it needed to be cuter, so here's the Panda: black-and-white with a panda face up front, and upcoming accessories adding a little bamboo flag, and a cupholder. The seat, front, and attachments all swap on the same core, so the bike can be updated to become whatever your kid's into.

On the spools: I designed the hubs around Bambu and SUNLU (reusable V3) spools since those are what I had piling up. Other plastic spools will likely work: skip the hub adapters and run the axle straight through the spool's center hole, or print a custom hub to fit yours. I'd be wary of cardboard spools though; I haven't tested any and can't vouch for them holding up.

Why I built it: After printing an entire wheelchair for charity I saw the power of large prints cleverly segmented with bed sized chunks. Between that and two kids, my empty spools were piling high and I wanted to find a functional use for them. Turning a pile of garage trash into something my kid can actually ride felt like the right kind of mission.

What's next: more kits, and whatever you all come up with — the bike has accessory points (documented in the build appendix) and is remixable, so build a kit for whatever your kid loves and tag me. I want to see them.

Safety Note ⚠️: Adult supervision, helmet, flat ground, and mind the 60 lb rider limit. It's a toy, not a way to get to school. Not responsible for any injuries or accidents that may occur.