last launch..

The microcentrifuge tubes that Bill shows work well. That is the only container I've used so far, and use it pretty much as Bill described - except I cut off the bottom tip with a hobby knife and seal the igniter in with parafilm. It can hold a max of 1.5g of black powder.

I have a limitless supply (I know a guy who knows a guy). If you let me know before hand, I can bring some to the next launch.

Claude wrote:

seal the igniter in with parafilm.

I've got to try that. I've had some parafilm for a while that I thought might by useful for masking paint. I never had any luck with it. Not having to scrape gobs of hot melt glue off my bench would be a big plus.

It can hold a max of 1.5g of black powder.

Which is more than enough for a 4" body tube of moderate length. Since that nice plastic cap never lasts more than one use, you could take a used one and make a ring of masking tape at the top allowing you to use a lot more powder.