Image link: https://imgur.com/9C6G4dm
Finished one, it looks like this. (This is running WLED on a D1 Mini with 6 LED's per strip and the strips are running up and down the stick and grouping set to 6 and using Police All Effect. This is using 30 RGBW LEDs/m)

Made a customization for the IKEA GRÖNÖ Lamp. There where a couple already on here, but they did not fit my needs. The one with only top part, had a spiral down the middle, where I just wanted it flat, plus when controller glued to the top, it was visible when lamp was on, plus the wire had to go all the way op to the top. The other one, I just couldn't see as very easy to print, it needed a lot of support, and that would take to long to clean so it looked good.

I wanted a bottom compartment for the controller and I wanted a lid, so the stick in the middle would not be visible. This is what I made. The stick fits perfectly inside the lid, so it's held in place. There is a hole for the wire in the base part, the stick is slim enough so the LED strips can fit through the hole with the stick.
I haven't made the Lamp yet, but made one with one of the other designs, where it was only a lid, and it looks really good.

I am using a NodeMCU, but switching to D1 Mini when I get that in the mail, since it is smaller, and fits my needs fine. The firmware on the controller is WLED, it is really nice, easily integrated into Home Assistant, but if you are not using Home Assistant, it also has a stand alone App, where you can control everything if you are on the same network as the light is.

I have printed this with White PETG with 2mm layer height on my Ender 3 pro where the nozzle was 235 Celcius and Bed was 55 Celcius and Extrusion Multiplier set to 0.95.

I have included two different sets. The one in the pictures is where the fillet edges on the base is 5mm and the top is 7mm. The 7mm fits perfectly on the top and the 5mm is a bit sharper than the lamp at the base.
The ones in the picture is GRONO Base v4 (5mm fillet edges) & GRONO Lid v7 (23.2mm Circle, 4.2mm Offset).
These fit perfectly, the base wraps around the bottom part, so it still looks good, and holds the lamp still, even without the top part attached. The top part fits perfectly, both around the base stick and inside the lamp with the extruded part. I have included the one with 4.5mm offset on the lid, because if the lamp is a bit tighter at the top,you can print this and get a but more room. And the stick was a bit tighter than I wanted, but still fit perfectly.

But I recommend starting out with printing the ones I have mentioned above, because these fit perfectly for me. But if you want, try out the base with 7mm fillet edges, because that one should fit even better, but haven't gotten around to trying it out, since the print takes around 10 hours.