Refining and modifying the fence stop

Having designed and printed the fence stop for my simple fence system, I decided that I could refine it and also build a flag stop. There were a few things that I needed to think about and it took several iterations before I got what I thought was a workable design. I use Tinkercad because it's easy and simple. But it is limited, and if you need to disassemble something and make a change, it can sometimes throw everything out. I'd like to get to grips with a better CAD programme, but I've struggled with Fusion 360 to grasp the concepts and methods.

So, here's a screenshot of my Tinkercad design.

I took the basic stop and added tongues to help guide the stop in the aluminium track. Since this version I've made the gp smaller to see if that helps keep the T-nut from turning when you try to locate it in the track. 

The flag stop has a simpler block with a hole and recess for a hex nut in one end. The idea being that you can glue or friction fit an M5 nut or bolt head in it. 

By chance the hole behind the hex recess in the end is tight enough to screw an M5 bolt straight in, so no nut needed. But it might work loose over time so a refinement is probably needed.

At the moment I'm printing a new version with a recess about 6mm in for the end to take a nut dropped in form the underneath.

If it works, then you could add a little epoxy to secure the nut in place but given you're not likely to keep undoing the the flag, it's probably not going to be necessary.

In use the stops and flags seem quite sturdy. There's very little deflection in the flags