Note: This is an upgrade/addon for the tamper that comes with the Cafelat Robot manual espresso maker. If you don't have this particular device, I am afraid, this will not be of much use to you.
Like the Robot (espresso maker) itself, its tamper is a beautiful, minimalistic design, engineered for the specific needs of those deep espresso baskets. But it takes a good eye to apply it perfectly straight and level, and it is not very convenient to apply pressure to the coffee grinds (not that you need much).
Thanks to the minimal design of the Robot's tamper, it was rather easy to improve on those issues with a single part that can be slid onto the original handle. It provides a convenient grip, ensures that the tamper is kept straight inside the basket, and gives you something to press down on. As a nice side effect, the tamper can now lie on its side without rolling around. All this probably won't make your coffee better, but it makes your routine of getting there just a little bit easier. The only downside I can think of, is that the tamper won't fit through the Robot's hands any more.
To secure the 3D-printed part to the handle, I use an M3 x 20mm screw with a hex cap and an M3 hex nut (2.3 mm thick). The nut can be slid into a slot at the bottom, and the screw goes sideways through one of the three sections that keep the tamper straight in the basket. Only little torque is needed on the screw to secure the part on the steel tube.
There is also a levelling tamper for the Robot that you can buy as an original part from Cafelat. I thought is was only fair to mention that. Also, after using my own for about two weeks, I discovered that someone else already published something very similar over on Thingiverse.