YOU CAN BUILD A 3D PRINTER THAT PRINTS UPSIDE DOWN AND FOLDS INTO A FILAMENT BOX
A 3D printer that prints upside down, folds flat, and fits inside a filament box when you are done.
by Audiotronix
WorkshopOpen-hardware
- difficulty
- ●●●●○
- time
- two weekends
- license
- GPL-3.0
- repo
- repo ACTIVE343 stars
●●●●○ · two weekends · GPL-3.0 · 343 stars · repo ACTIVE
WHAT YOU’LL NEED
- 3D printer + filament — printable parts — files are in the repo
- Electronic parts — full list with part numbers in the repo BOM
- Dev board / microcontroller — runs the project firmware
Partner
COMPAREE VERDICT
Positron LT is the RepRap version of KRALYN's Positron V3: every structural part is 3D printed instead of CNC-machined, so you can build it with an ordinary printer and parts from normal suppliers. The form factor is strange and clever — the print bed is a sheet of glass above the nozzle, the part prints hanging underneath, and the whole machine folds flat when you are done, small enough to fit inside a standard filament box. The payoff is portability; the cost is that you are building a machine with 50+ printed components, an integrated 200 W power supply, and GT2 timing belts on X and Y, and the assembly documentation is workable but not polished. You will be referencing Discord threads, comparing your build to photos, and working through small hardware revisions as the project updates. The single thing most likely to go wrong is assuming the documentation is complete: it is not. The BOM is published, the STLs are there, and the firmware config is in the repository, but you are going to spend time figuring out small details that are obvious to the community and invisible to someone building their first one. This is a clever second-printer build for someone who wants a portable CoreXY and is comfortable improvising around gaps in the instructions. If you need a polished assembly manual, this is not it yet.
IN THE REPO
NOT IN THE REPO
- —Complete bill of materials, STL files, and Klipper configuration are published under GPL-3.0, which allows commercial use.
- —Assembly instructions and wiring diagrams are present but not comprehensive — expect to reference community Discord and look at photos.
- —The repository is marked as a work in progress and is updated continuously; expect hardware revisions and small changes to the BOM.
- —You need an existing 3D printer to make the structural parts; there is no CNC machining required, but the part count is 50+ printed components.
- —No video assembly guide from the creator — community walkthroughs exist but are scattered across YouTube and Discord.
- —Design by Audiotronix, based on the original Positron V3 by KRALYN, which required machined parts and exotic Synchromesh wire.
Can I build this?
This build involves mains voltage — for adults comfortable with electrical work only.
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
Partner · KickstarterHeyGears G1: 10M+ colors and transparent parts in one print, plus UV printing on flat objects. Figures, parts and labels — no painting.
Gallery
Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Read the README and the work-in-progress disclaimer (The project is openly marked as evolving; check for recent commits before ordering parts.)
- 2.Download the BOM spreadsheet and verify part availability(GT2 belts and MGN12 rails are standard; check lead times on the Revo Voron hotend.)
- 3.Print the structural parts on your existing printer(50+ parts; print in ABS or ASA for heat resistance near the hotend.)
- 4.Join the community Discord for assembly support(No direct Discord link in the repo; search for Positron or Audiotronix communities.)
KNOWN ISSUES
- Assuming the documentation is complete — it is not. The BOM and STLs are there, but assembly steps rely on photos, Discord threads, and your own experience with CoreXY printers.
- Ordering parts before checking for hardware revisions — the repository is a work in progress and small BOM changes happen; read recent commits first.
- Printing the structural parts in PLA — you need ABS or ASA for anything near the hotend or heated bed.
- Expecting a plug-and-play Klipper config — the firmware is provided but assumes you know how to calibrate motion, adjust bed levelling macros, and tune pressure advance for an upside-down print.
- Building this as your first 3D printer — you need an existing printer to make the parts, and the assembly expects you to know what a properly tensioned GT2 belt feels like.
- Underestimating the part count — 50+ printed components means a week of print time on a modest machine, and any failed print adds to the schedule.
Can I buy a kit?
No. This is a self-sourced build; you print the structural parts and order the motion components, electronics, and PSU yourself from the BOM.
What is the print volume?
Not specified in the repository; the original Positron V3 was around 180 mm³ — check the community Discord for confirmed numbers on the LT.
Why print upside down?
The inverted layout lets the Z axis collapse into the base when you fold the machine, which is how it fits inside a filament box. The print quality trade-off is debated in the community.
Do I need the Revo Voron hotend specifically?
The BOM specifies it, but the mount may accept other Revo variants or similar 25 mm diameter hotends — confirm in Discord before substituting.
What changed from the original Positron V3?
LT replaces CNC-machined parts with printed ones, swaps Synchromesh wire for standard 3 mm GT2 belts, integrates a 200 W PSU, and reduces the part count. The folding mechanism and upside-down print layout are the same.
Community builds
No community builds yet — be the first, we feature the best ones.
Discussion1
FROM THE COMPAREE TEAM
The whole machine folds flat and fits inside a standard filament box — portability no normal printer offers. Would you actually travel with this, or is the appeal just desk space when you are not printing?
Audiotronix
Audiotronix designed Positron LT as a RepRap-friendly version of KRALYN's Positron V3, replacing the original's CNC-machined parts and exotic Synchromesh wire with 3D-printed components and standard GT2 belts. The goal was to make the folding, portable form factor accessible to anyone with an existing FDM printer and parts from ordinary suppliers.
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DISCLAIMER
- Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
- Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
- Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
CompareeTEAM9d ago
Practical notes from our verification: the repository is openly marked as a work in progress and is updated continuously, so hardware revisions and small BOM changes happen — read recent commits before ordering parts. There is no official assembly video from the creator; the good walkthroughs are community-made and scattered across YouTube and Discord, not linked in the repo. The single biggest surprise is the part count: 50+ printed structural components means a week of print time on a modest machine, and the documentation assumes you have built a CoreXY before. The BOM, STLs, and Klipper config are all published under GPL-3.0, but you are going to spend time in Discord threads filling gaps the instructions leave open. Footage credited to KRALYN 3D, who also created the original Positron V3 that this design is based on.