Disclaimer

I take no responsibility for your actions with the supplied files, if you should decide to make it, or if you are not legally allowed to own such a airsoft gun according to the laws of your country, state, province, community and yet still decide to make it. This is an airsoft gun only, not a real firearm, however it can do damage if aimed at the wrong place or direction. Treat it responsibly and use the appropriate safety gear. Use caution and point in a safe direction when folding and unfolding.

Started working on this almost a year ago. Thought it would be cool to have a functioning airsoft folding 19 after seeing one on season 3 of WestWorld. I already had a sort of functioning FPG at the time and used the lower off that design to make the folding 19. It's compatible with WE and maybe TM G19 variants. This design will not work with the EF version. Have had better luck with ABS over PLA. The main issue I've had with PLA is breaking at the pivot point on the grip. The backstrap might be a little tight and could require cutting or sanding to make it fit.

The pin for the back of the grip is 1.68 mm diameter and 21.8 mm long. The top pivot point pin that fits into the grip and lower are 2.5 mm diameter and 25.4 mm long. The grip spring I cut and made sure it fitted. The trigger spring I had to cut and shape, which is more tricky. The files are free to the airsoft community and are not to be sold or purchased anywhere.

Troubleshooting

These are some of the issues I've had while developing the airsoft folded 19.

The slide won't stay on.
Check the length of the end of the trigger spring making contact with the lower. It might need to be shortened.

The grip will not stay locked in place.
Check the spring to make sure it puts enough tension on the retaining clip.
Check and make sure the retaining clip is not broken.
Some cutting or sanding might be required for the retaining clip to properly fit in the groove. It should be even or slightly inside the groove on the lower.

Grip will not stay folded.
Check the pivot point on top of the grip to make sure it's not broken.
Sometimes the part that holds the grip folded can break or is cut too far back.

Grip can't lock in the fold position.
The part that holds the grip needs to be sanded or cut back to accommodate the grip.
The standard 17 size mag can lock in but the 19 size mag can't and will make it push out from the folded position.

Slide not locking back.
The follower on the mag doesn't make contact with the slide catch. I've had some mags work perfectly with it but then not work other times. Other mags it just won't work.

Mag is too tight inside the grip.
Make sure to get rid of any bumps or inconsistencies in the magwell. A light sanding inside the magwell can fix this issue.

Mag dumps gas and doesn't fire.
It's either a issue with the hammer not hitting the mag all the way, mag movement when hitting the mag or with the top of the mag not sealing properly with the loader nozzle. I've had some mag that just will not work at all but others that have never gave me a problem.

Trigger will not unfold.
Check the spring on the slide release to make sure it's not stuck in between the trigger and slide release. It can cause friction and make it where the trigger will not unfold.
The trigger can get stuck inside the lower. Cut or sand the end of the trigger till it doesn't get stuck.