A key challenge was managing the size of everything. The thermal camera unit itself was fairly compact, but if you're going to add thermography to a tool, you want to have a big, clear display to view it on. So we gave it one. But then you have a camera and a big display to power, so you want to give it a big, beefy, rechargeable battery pack that will last longer than a single job. So we did.
Now you've got all of this in a rugged case that still needs to fit into the user's hand. So it became a game of cutting away unneeded space, and adding some strategic bevels and rounds. The end result is that despite the meter's size, you have a "contact area" with the hand that is significantly smaller and comfortable to handle.