How to place a label(sticker, like rectangle, triangle or QR code) and make sure if the part present next to it

I am doing a project where I need to make sure if the clip is placed to certain position in holder. AS you can see, the holder has 5 holes, but we are using only 3. I want to make sure that a holder has the part and if it is missed, identify which hole is missing a part and grab part from a bin and place it there. I can place a label next to each hole, like a triangle sticker, rectangular sticker or QR code, and my idea is the following: look how many parts are identified, if it is less than 3, then look at each label and search like 30mm radius, if we have a part present. I attached a photo, so you have an idea.
I am using MM Suite 1.7.4
Eye in Hand
UR Robot UR5E
Nano Camera
As for the Vision steps: I have
Take picture → apply DLK and extract 3D point cloud → apply mask to point cloud → filter → 3d coarse matching and 3d fine matching → send to procedure out.
You can take at my previous question, where I have full video of Vision software if you need to see. Thank you very much for all your help.

Please provide as much as possible detailed information about your questions, so that the technical team can provide the most relevant answers.

As my understanding is that you want to check if there are clips missing from the holder. If your holder is fixed and not moving, I think you can just create 3 different ROIs, each ROI cover a clip, and then check if there are any point cloud in it by “extract 3d points in 3d roi”. If not, then a clip is missing.

Can you please explain more. Do I need to create 3 different 3D ROI steps? Or I can do it from 1 3D ROI step? how do I handle the output?

yes, you need to create 3 different 3D ROIs, after that you can refer these steps:

When there is no point cloud within a specific ROI, it indicates that the corresponding workpiece is missing. The corresponding label will be output. However, it’s important to note that using this method assumes that the position of your holder remains unchanged because the ROI’s location is fixed.

Alternatively, you can use another approach: start by 3D matching to locate the holder’s position, but set the holder’s pick point above the holes. Then, create three rectangular prisms using the “Extract 3D Points in Cuboid” step. Subsequent steps will be the same as in the previous method. The advantage of this approach is that the holder’s position can be freely adjusted.