I recently acquired a set of BMW City Cases that need some TLC.  One has a crack about 2 inches in length.  I plan to drill either end of the crack and infill it.  What is the recommended goop for this?  J P Weld? Another epoxy? What will give a long-lasting repair? I think I once viewed a video of a repair by "welding" using plastic tie-wraps. Is that recommended?  Who has experience with that? 
The cases are weathered, but very serviceable. I'd like to dress them up with some paint.  Satin finish? Matt?  Any suggestions pro or con?

G'day Brickrider2,
 I also brought myself a set of city cases. Although mine are ex police (white). One already had a repair to which was expoxy repaired (inside panel) seems to work fine.
 Unfortunatley one bag dislodged itself from its frame after hitting a large bump in road & skidded down the tarmac.causing road rash on the outer lid.
I fault myself thinking I did not connect it sercurly to mount. I was happy my 6 pack of beer survived but my pie & saugage roll were smashed. First time I ever took a 6pack to my mates place as not a beer drinker. Lesson learnt though, Mate always has plenty of beer.
I was thinking prior to road rash weather I should paint them or not as white cases do not match white on bike. Now I do not have a choice. I was thinking satin black also. After visiting Autobarn I am now considering a wrinkle finish black (comes in spray can) think it will give a nice finish. I am going to use a spray can of undercoat specficaly for plastics though.
My cases being ex police bike my outer lid seems to be fibroglass, inners are plastic. Regards Poddy

There is also a panier repair thread in the how to posts

Thanks for the tip re the thread on pannier repair.
I considered using a crinkle finish paint for this job, but I suspect it will be more difficult to keep clean, or at least the appearance of clean    I think satin is the go here.

Various paint suppliers have various textured paint, I believe Standard K used one by Rustoleum that is a good match for the OEM finish. Paint, undercoats and fillers must be plastic compatible otherwise the paint could suffer adhesion problems.
Regards Martin.

After sanding & prep of my pannier lids. Found out they are also plastic. Came up a treat in hammertone black also helped to hide a few deep marks. Poddy

I did mine in satin black and I am very happy with the result.