You need to lay it flat when printing the small pins. I always print the pin with raft you can also add small 2x6 tap screw for more strong connectiom

This modular servo Mount is a part of Open Source Blocky Codes Modular Blocks, you can download all the parts on my profile.

This one is for SG90, you can use MG90 but only on horizontal positions, I will upload the mg90 version later.

Known bug: Sometimes the sg90 horn has a bit different size, so if it's not fit, you need to find your way.

I also add some STL's for blocks in this post so you can try it out.

Make sure your printer is calibrated. Each hole in this system is 7mm and the block thickness is 4mm.

visit https//blocky.codes to know more about this system.