Strengthened mtb bar plug

I had a bit of a problem with thatsmein3d's mtb bar plug (https://www.thingiverse.com/thing:2053933) in that it used very little material in the middle to hold it together, so i strengthened it a bit + added a bit of flare by combining it with SuperClam's punisher skull (https://www.thingiverse.com/thing:463900). Recomend using a bit of insulation tape on the inside thread to create additional friction and secure the plug inside your bars with more confidence.