I have an indicator enclosure that has part ridges within the hollow space for the bezel to lock into however I have recreated the modle but cannot find assistance in creating the lock ridges 
i first thought it was a thread but they are horizontal, they ar only on the two sides, see picture
I can’t see them that well and I’m on my phone at the moment but I would probably use Follow Me to create those. Might make sense to create a cross section of the whole thing with the rib profiles outlined and use Follow Me around a circular path.
@DaveR has the right idea.
The only thing hard about using “Follow Me” is that the profile has to be orthogonal to the path.
Here is your original model with seven, evenly spaced square ridges added.
240918A_Rear_Indicator_Cup_M4.skp (737.6 KB)
Also … the ridges are their own “Group” … so they still need to be “joined” to the cap.
Meanwhile … there are also the two “vertical slots” in the ridges that need to be added … by removing some material. And that might be done more easily before combining the ridges and the cap.
And now that I look at the image of the cap again … it looks like there are only six ridges … NOT seven. So much for my counting skills.
See this SU file for ideas.
Cylinder with internal ribs.skp (319.2 KB)
Thank you all but I have gone with @egodsey 's answer (modified a bit but I was ahown the correct path to take
240918A_Rear_Indicator_Cup_modded ridges (grouped together).skp (739.7 KB)
Seems like @DaveR was suggesting the same approach … regardless, glad it worked out for you.
But, your model only has three ridges … and from the photo of the original cap … the cap has six ridges.
Your counting is as off as mine!
Yeah the Bezel only has 3-4 ridges but the 3 work fine, Sorry for the delay in replying, been in hospital)
