How to attach attachments (Need help)

How do you attach attachments?

So basically I have this meshpart here where the size isn’t exactly fit to be just put in the same position as the leftlowerarm, so I created an attachment in it and I want to move the part relative to the attachment onto the attachment of the leftlowerarm so it fits.

- Br, iSyriux

Is there a reason you can’t use a WeldConstraint? That would keep it wherever you place it in Studio.

Otherwise, you set a Weld (like through a script) with the C0 as the main attachment’s CFrame and then the C1 to the secondary attachment’s CFrame. Don’t use the WorldCFrame because welds/motors/etc work in relative coordinates.

I can’t use WeldConstraint because it attaches parts together, not attachments. As such, I am unable to achieve the relative offset I desire in order to make the shield fit on the arm.