This is a solution I devised after loosing so many bids on Cones!!
Standard rubber Tap Washers.....
Make a loop of Shock Cord and tie through the washer, leave a little bit of give so the head can move.
To make it easier soften the head slightly with a hair dryer or steam over a kettle, push the head
onto the washer, it should click when in place....and viola!...you'll have the best head replacement ever!
The Rubber in the washer should give the head more grip too so you can achieve better posing!
These are standard washers you should be able to get them anywhere, even local Shops should
have them as standard!
There are other applications for this fix too.....
BBI G3 body.
Modern Joe Body.