This is the second iteration of this chair. The steel frame is made of 3x3 inch thin wall tube (.065 inches) so the parts are made for that. The arms which I have not done yet are scaled for 1.5 inch tube.
I used 5/6-18 Nutserts and ended up getting a 50 pack from amazon.
The back is not really held in place other than a slight friction fit with the backing. I am going to build a different mounting system but it works for now.
https://www.amazon.com/LOKMAN-Pieces-16-18UNC-Threaded-Knurled/dp/B07BFVDKKG/ref=sr_1_4
Also bought the pneumatic tool and its so much easier than using the lever arms
https://www.amazon.com/Astro-Pneumatic-Tool-Capacity-Setting/dp/B0B2DLBPJ5/ref=sr_1_1
The legs attach to the chair with these and use pins similar to this to lock into holes that were drilled with the drill template.
https://www.ruffstuffspecialties.com/R1292.html
https://www.relentlessfabrication.com/collections/tire-carrier-components/products/spring-loaded-t-knob-lock-pin
Seat Belts:
https://www.alibaba.com/product-detail/Two-Point-Safety-Belt-Aviation-Buckle_1601083634919.html?spm=a2700.shop_plser.41413.2.2b6f27af6gkyxQ
It was cheaper to buy the Min Order Quantity then to get 10 of them elsewhere:)
For the arms I am going to use these:
https://www.alibaba.com/product-detail/Portable-Adjustable-Aircraft-Safety-Belt-Extender_1601486473111.html?spm=a2700.shop_plser.41413.2.2b6f27af0X6v1q
The lower leg part with the seatbelt is too tall for a MK4 so you can slice it in half. I ended up cutting the tab off the belts and putting the tab in the “buckle” part.
The author marked this model as their own original creation.