Zither pin and tuning peg question

I have thus far been using guitar or ukulele tuning hardware, but have been working on making very light instruments for taking on backpacking and long (multi-week or multi-month) bicycle touring trips. As a result I am thinking of zither pins, violin pegs, or home made pins.

I am unsure about how to go about fitting the pins or pegs. Are they just pressed into drilled holes or do I need to make tapered holes for them? If so how? Does it require a special reamer? How thick does the wood need to be to properly support the pegs? Will they work in less hard woods like poplar or even aspen?

Also since weight is a concern and I have a lathe, is there any reason not to make aluminum pins and possibly hollow ones? I was thinking that rather than square ends like zither pins I could just slot the ends for using a coin as a wrench. I guess I could do the same with wood pins, but might need to sleeve or wrap the end near the slot to prevent splitting.

The lack of knobs would allow the pins to be closer together and therefore make the instrument a bit shorter and lighter.

Thus far my lightweight experiments have been limited to small (25" or so overall) stick dulcimers that have weighed in the 7-8 ounce range or so. All have come out OK and one in particular came out very well and has been great fun to play. At that weight I figure there is still room to go a bit lighter.