I started working on one of my favorite flashlights. Streamlight's SL 20X. It has a great switch, but a very small head which makes it hard to do much with.
Here is the first step...the pill. It's 1.400" tall and 2.420 in diameter. What you see is the bottom. I haven't machined the top yet. The fat part on the bottom will be parted off the rest of the way later.
Finning / Grooving thread here. https://budgetlightforum.com/t/-/23587 Contains many more pics and the general progress of the build.
Tagged to follow. I have a few sl20x’s laying around and have been wondering what to do with them without spending a ton of money. Maybe this will get me motivated to put in some work on them.
That pill looks clean so far. 
You don’t need such smooth surfaces, except to look at.
Beautiful shot! Looking forward to your mod.
That's true, but I like to try for the best surface finish I can get.
My first 20x mod used an optic. Direct driven XM-L2 on 3 D cells. The heat sink weighed 80g.
My other thread on grooving / finning kind of took over. So, I put a link to it in the first post.
Here's a teaser.
Oh wow! The head on that thing looks massive!