Anything like the Sofirn C01 ?

If you know the basics of reflow soldering and want a neat DIY project, you can make a low output, single mode driver, and possibly find some existing light to fit it in, or get creative crafting your own peculiar body.

See this post, for a simple Joule thief design, including a parts list, and a link to where you can have the PCB that gchart designed for it custom made: