Or, from your property menu you click on the thickness dimension (it appears if you click on the function first)
Either you name it in the field "epaisseur@Tôlerie 1" if your function is called Sheet Metal 1 (which is usually the case) or with the name of the function that is fine. For example, if you want it to indicate Sheet thickness 3 for a thickness of 3, you put Sheet metal thickness "epaisseur@Tôlerie 1"
Otherwise if you have the smartproperties you have the property referenced "Sheet metal thickness"
Otherwise the solution of coin37coin works very well, I used it for a long time before replacing it with the one of smartproperties.
On the other hand, if you have the misfortune of having a part with sheet metal2, you have to rename it to sheet metal1 so that it marks the thickness
EDIT: Be careful with the 1st version this coin37coin which works very well for sheet metal parts made since SW2013 or 14 I don't know anymore but not before.
They are recognizable because the sheet metal function 1 or 2 is included in a sheet metal folder and not the one made before this version and therefore the Epaisseur@Tôlerie property only works with this folder.
Otherwise, you use the "Thickness" variable which is created as soon as a part is sheet metal (which also gives access to the "Link to thickness" option in extrusions!).
You create a "Thickness" property with the value "Thickness".
In your drawing, you create a note that fetches this variable. (that you can put in your cartridges)
No worries coin37coin I don't know exactly the problem but since 2014 we were in 2012 before, we had a problem to recover the thickness with one of your 2 ways I don't know which one didn't work anymore on the new part (with a backrest).
Otherwise Benoit.LF's solution works well, it seemed to me that it was a problem in some cases but no matter how much I tried it I can't find which one, the bug may be corrected or I can't identify it anymore
Edit: I found thanks to the axemble support the property it even worked very well it's just that I couldn't concatenate it with the bend radius (solidworks bug impossible to concatenate the thickness property under sw2014)