17 TSE and Filters

I recently picked up a 17TSE and would like to use ND grads on it if possible

Lee make a push on filter holder which is 100mm diameter so it will fit over the lens no problem but there are no adapters available to make it small enough to fit snugly as the lens is about 90mm diameter. Also I think it may sit too far back on the lens to clear the bulbous front element

Has anyone here used this system and made their own adapter? I have seen a solution using a butchered lens cap and set screws but I am pretty useless at DIY and would prefer to get something ready made or at least involving minimal effort

The Lee filter holder SW150 is for the Nikon 14-24G and uses 6X7" filters. It clamps in front of and behind the Nikon lens and was not built to fit the 17 TSE. I have seen several solutions for GND for the 17 TSE based upon adaptation of a lee foundation holder (4" filters). They are all DIY, and if this is not your thing, forget it, as its a pretty fiddly solution. All solutions I have seen will induce some mechanical vignetting upon extensive shift and/or tilt. That is why the lens does not come with a built in hood.
Mike K