In this instance you need to use both Access Group and Individual User rules.
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The first step is to ensure you have turned on the Training functionality in your lab's settings..

We can use this setting to mark users as Trained on equipment in their individual user settings. If they are Trained on an instrument then they will be able to book it. You mark a user as Trained in the same way you would assign them access to equipment, by ticking the boxes next to equipment that they should be able to book on the Training tab in their user settings.

Now, create an access group with all the equipment that the users should be able to book and only view. Then also assign all the relevant users to the group. In the Access group settings, you need to ensure that you have selected to have a Separate usage schedule for booking equipment without training and that Hide equipment for untrained users is toggled to No. Then on the Schedule tab of the access group settings, you will find a second usage schedule for untrained users. Set all the days so that the Untrained users will not have any time to book the instruments.

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This setup will allow everyone in the group to see the equipment that is in the group, but only the trained users will be able to book the equipment. If the trained status changes for any of the users, and you want them to have access, simply add the relevant item to their individual profile (in the Trained to use section) and they will then be able to book the item.