So what your really asking is how do you add a control to a cell in a grid.
This is the closest I could find… But in your instance you would use a button then add the icon to that from here Material Design Icons a recent post from
here is another link that talks about adding icons.
I did try to have a crack at this myself, but to no avail…
Funnily when I try to look at the attachments slider on forms in AppStudio I can;t find them… @hmwillett am I just going blind?