Making your own arrows for big bore airguns

I dont know how well it would work but maybe some 3D printed bits might assist in this. 

I know where a guy screwed .410 shot cups (backwards BTW) to the base of shafts as the fletching and had some type of rubber ring behind the head to center it at the front in his .457 Texan.

He told me it sealed ok at the base and when it left the muzzle the air blast openned up the cup petals so they acted as drag fins. Did not see him shoot it though.

Actually use rubber wide band orings or failing to find that find some felt glue it to the base then use that rubber dip 

You may find that the hardest part will be to get your arrows balanced your cg should be two to three inches forward of center any more than that and they will nose dive on you but at the same time you don't want a tail heavy arrow or it will hit everywhere but where you are aiming 

You are going to have to work off trial n error

Few more things I thought of 

At the shot show when those arrows was demoed they used a smooth bore.

I don't know if it's a good idea to shoot them out of a rifled barrel and depending on the type of barrel you may be finding yourself fighting a choked barrel 

Even aluminum arrows will flex when shot this means that the sides of the arrow will flex and strike the side of your barrel on it's way out. So your risking messing up the rifling.

I will work on my side also, I have a bulldog will let you know of any breakthrough.

I've got some carbon fiber arrows 

You can buy raw shafts & cut them yourself-(My Condor arrow adapter has a tube that the arrow slides over and uses point to seal) in your case mimicking the air venturi would be necessary- so 3d cap or delrin cap turned on lathe slightly smaller(talking Thousanths of an inch than bore with o-ring groove to seal should do it.Fletching & glue and tips- if planning broadheads allow for xtra length (barrel length to breech +) Lighter the plug, the better the balance in my mind(weigh basic nock & try to match).