My main thoughts with your pack holders is it may be wiser to invert the mounting method to the pack, using the slot rather than the T stub on the part you print, equally on the larger holder adding one for each cell brick rather than just 2 outer one will give a much firmer grip, reduce dripping while the print head moves over the space, and allow them some time to cool into shape.
For the bolt points, i would thicken the walls up to 5mm thick where the bolts will be add a small 0.5mm chamfer on the top of the hole, and radius off where the stub for the bolt takes a 90 degree turn, doesnt need to be big, but anywhere the print head makes a sudden direction change and produces a speed wobble leaves an area weaker than a continuous deposit.
For the watt meter, i would suggest thickening where the bolts connect, and adding a hole nearby each bolt to take a standard chamfered wood screw head, so that it can be mounted down easily,
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 profile and I might add that.
The watt meter was just to have a base. I didn't want to bolt it down to anything.
But please feel fre to remix them and use them however you like. That's what they are there for.
I appreciate any and all input.