I would strongly recommend that "DIY" keep its own sub-forum....it's just too important and useful to be spread out all over the forum.
Also, "Physical Fitness Challenge" should be re-named into "Medical/Health & Fitness" (two birds with one stone). The mods can make an effort to move previous medical/health related topics into it over time.
@Admins
I'm not sure exactly how the software works, but for example, if you wanted to combine "News" and "Politics", and the only way it can be done is manually (one topic at a time), feel free to give any willing mod the assignment.
FOR EXAMPLE: Admin re-names "News" to "News & Politics", then assigns a mod to move all topics from "Politics" to "News & Politics". Then admin deletes the the empty "Politics" sub-forum. Like I said, I'm not sure what exactly the admins can do with the software, but if there's not an easy way to combine sub-forums just let us know...I'll be glad to help.