To use the slot it would have to be printed vertically. The t hold just fine and is not going to break off. I yanked the crap out of that thing. It didn't budge. I don't think k it needs to be any thicker it would just add bulk. I can see where countersinking the heads would make a nicer looking...
Watt Meter Holder With Binding Posts.
Small Pack Hold Down.
Large Pack Hold Down.
Let me know what you guys think, and if they are any use to you.