The Unity case from Kiwi Electronics is laser cut case which can be assembled quite easily. It protects the Raspberry Pi and HATs quite nicely.
Please note: The correct order is required to prevent breaking the acrylic. You should be able to assemble the case without too much pressure.
Remove all protective foil before continuing.
1. Start with the bottom part. Use the included long 10mm screws, plastic spacer and nuts. The spacer is needed for the correct height of the Raspberry Pi. Next, you can place the Raspberry Pi as shown.
2. Place the standoffs that are included with the PoE HAT and place the HAT.
3. Place the 10mm M/F standoffs that are included with the case.
4. Place the front plate over the USB and Ethernet ports. Next you can carefully place the side plate in the sockets as show below. A little pressure is no problem, but be careful not to press to hard.
5. Do the same with the back plate and the closed side plate. This bit will be much easier.
6. Finally, place the top plate and use the 6mm screws to secure all plates.
Now you can place the rubber feet and place the microSD.