GoodAmount

The Manticore 3D Printed Non Conductive Shaft Extension was designed to alleviate issues caused by having a conductive carbon fibre lower shaft bolted directly to the coil. This is particularly important for gold prospectors who experience knock sensitivity when laying the shaft flat against the coil during target recovery, but it may also have benefits during the target search, especially when working tight rocky terrain where the coil is constantly being knocked and/or rotated relative to the shaft. The product has been designed in three parts so that the layers can be 3D printed in line-of-force to increase strength and prevent delamination during use.
You will need to buy 2x 40mm M8 nylon hex bolts and nuts - I sourced mine from here.
For each assembly, you will need to 3D print 1x shaft extension, 1x clamp, 1x clevis and 2x thumbwheels. To assemble, glue the clevis to the front of the shaft extension (preferably with epoxy) - it’s been designed to only fit to the front to avoid mix-ups. Glue the clamp to the rear of the shaft extension, making sure that it’s oriented in the same direction as the clevis mount (facing upwards). Seat the M8 nuts into the clevis and clamp rebates and the two 40mm bolts into the thumbwheels. It's helpful to epoxy the bolts and nuts in place, but be careful not to get glue in the threads. Snap the shaft-extension assembly to the Manticore’s lower shaft, thread its stock bolt through the clevis and tighten in place. Thread one 40mm bolt/thumbwheel through the rear clamp and tighten (avoid over tightening) and the other to mount your favourite coil to the 3D printed clevis. Happy hunting!
Creative Commons licence - CC BY-NC-SA

The Nox 900 shaft extension was designed to alleviate issues caused by having a conductive carbon fibre lower shaft bolted directly to the coil. This is particularly important for gold prospectors who are experiencing knock sensitivity when laying the shaft flat against the coil during target recovery, but it may also have benefits during the target search, especially when working tight rocky terrain where the coil is constantly rotated relative to the shaft.
You will need to buy a 40mm and 60mm M8 nylon hex bolt and 2 nuts - I would suggest just buying two 60mm bolts and cutting them down to size. These are the ones I sourced - https://www.aliexpress.com/item/1005003554528145.html?spm=a2g0o.productlist.main.1.138c674cdkh3Wv&algo_pvid=949ce8d2-8033-47ba-8524-5b8b03a83770&algo_exp_id=949ce8d2-8033-47ba-8524-5b8b03a83770-0&pdp_npi=4%40dis!AUD!24.72!12.12!!!16.16!7.92!%402103011017185920473694307e26fe!12000026266634715!sea!AU!136322599!&curPageLogUid=mOIvLzytoqPb&utparam-url=scene%3Asearch|query_from%3A
For each assembly, you will need to 3D print 1x shaft extension, 1x shaft extension clamp, 1x clevis nut seat and 3x bolt thumbwheels. To assemble, glue the clamp to the rear of the extender (preferably with epoxy), making sure that the area that mates with the stock shaft clevis is in the right orientation facing upwards. Seat the 60mm M8 bolt into the clevis nut seat and the 40mm bolt into one of the thumbwheels. Seat an M8 nut into the other two thumbwheels. It's helpful to epoxy the bolts and nuts in place, but being carful not to get glue in the threads. Remove the rubber inserts from the stock carbon-fibre-lower-shaft clevis and place them in the 3D printed clevis. Insert the clevis-nut-seat/bolt into the stock carbon-fibre-lower-shaft clevis and use one of the thumbwheel/nut assemblies to tighten in place. Snap the shaft-extension assembly to the stock lower shaft and thread the 40mm bolt through the clamp and tighten with the other thumbwheel/nut assembly. Attach your favourite coil. Happy hunting!
Edit: Creative Commons licence - CC BY-NC-SA

This skid plate adds extra material to the leading edge of the skid plate to allow greater wearability when scrubbing the coil on rocky terrain.