At the moment tinker modules are sharing cd with potions like Potion of Hushed Zephyr, Shocking Disclosure and probably some more which I dont have in the inventory. This makes some tinker modules completely useless.
For example, Plane Displacer Module that makes you invisible - 10 min cd and quite high chance of malfunction that will trigger cd anyway even if it fail. I have no idea why you would want to use this if you can use potion of hushed zephyr that is guaranteed to work and have 5 min cd. 50% cd, guaranteed to work and cost like 3g on my server…
10 min cd is also too long. Longer even than lay of hands. Loh have 7 min cd, one of the longest in the game because its impactful. If you use it, it means you want to invest a lot of your resources into beating the enemy and you’ll probably will because it makes your health basically doubled for this one fight but tinkers are not as impactful like this and have a chance of malfunctioning. Engi can spec into mechanical mind to reduce chance of malfunction but what about everyone else who will have tinker on bracers?
At the moment using tinkers without engineering can make you killed… When I tried to test some modules, invi module failed 2/3 times. Once it polymoprhed me into a critter and then second time it reduced my size and main combat stat for some time. Its completely unreliable and even if it fail, it’ll trigger 10 min cd on other potions. You are safer not to use it if not engi than to use it but Im pretty sure that was not Blizz intention when they were making this.
To make it viable I suggest to separate its cd from potions and reduce cd to 5 mins. Every impactful battle potion have 5 min cd. Saltwater Potion that is increasing your damage by 30% in bgs also have 5min cd. Use it with your main combo and it’ll be impactful.
Also, cd can be lowered to like 2.5 mins if malfunction happens and rework malfunction effect. Basically, if malfunction chance is too high, nobody if not engi wont be using this. Lets make malfunction just not trigger positive effect but remove negative effect.
10 min is far too long. Im pretty sure tinkers were introduced because they were supposed to make the gameplay more interesting but 10 min with a chance to fail wont impact our gameplay at all.
I dont want tinkers to be overpowered but some changes are necessary because now its not viable. Im open to suggestions 
Edit: Sometimes if it fails it triggers 5 min cd. When polymorphed 5 mins, when stats lowered 10 min.