What size container?

[Eutycus]

That's what I've always heard, it's not just the spark but a certain amount of heat is needed as well.

 

[Flinty Scot]

A variant on the crimped & leaded copper tube might be sections ofg small diameter (1/4 or 3/8")copper tube, with bottom wooden dowel plugs, trimmed flush and glued in, corks to seal the tops, and a wooden loading block, drilled to accept the tubes.

A bit of work, but it could be elegant, in keeping with the period and style of the guns, and a good display piece for onlookers. This would seem appropriate to me, even for an "in period" bench shoot.

(I think I've just convinced myself. to work one up for my target rifle.)

 

[Musketeer]

Static has NEVER been proven to set off any black powder

Correctamundo. I'm fairly certain this link has been posted here before, but that was many moons ago, so:

BP Static Test

 

[Rifleman1776]

If plastic "builds up static electricity" why are all the reloading funnels & powder bottles made out of it???

They aren't "all". Mine are brass. My modern reloading stuff was plastic. As to "why?", the answer is they are cheap to manufacture. If you think plastic stuff has a place in the ml game, go for it.