I saw a alloy swedish head oil cap plug on the forum somewhere and can't find it. Would anybody know if it was a one off or are they manufactred for the LS, and if so could anybody have an address as it would be my answer to fit it, as the plastic rubber one we have heats softens shrinks and distorts with the running of the engine and it is only a matter of time untill even a new one leak's. Maybe the guy who made it is selling them, I would like to get in touch with him,,cheers

Nope haven't made one yet, juggling too many plates.
I asked, and got answered, maybe with the reference kenny is asking about.  

Got it and THANKS it looks just the job, got my daughter to print the picture, so I will be going up to our local tech college tomorrow

With a bit of ally bar and the picture and the cap, and some pretty fancy words to get the students in a flap, to lovingly construct a bonnie little plug, that'll keep the oil internal and a BIG grin on my mug,,,,,,,,,

OK, had a moment to look at it (amazing what you can do with a spare engine in pieces on a bench)
1st, the design of the plug prevents it from being blown in. (just in case someone shooting rpgs at you, wouldn't want to start leaking oil cause of that) So while we may make something to replace it, getting it out will still require taking the cover off.
2, the screw that you not supposed to remove when removing the head cover is over it, a little to one side.

So I had a plastic plug left over from something I bought and it fit in very loosely.  Mod'd the cap so it was just a thin lip and drop it in the hole.  Placed the cover back on the head to test to see if I can get it out.  Yes, I can pop it out from under neath.  Reach in with a forceps and work it out between the valves.

So it's very promising replacement.  I'd use that "do not disturb" screw to hold it in place.  Just need to replace it with one long enough.