About this 3D model

I have designed my second version of the follow focus just like the pictures,but I wil publish it on the other "thing",after I finished my total tutorial,i will stick the link to this theme。(this design I knowed that it is a little difficult for makers to make one because it needs some customed made part like the worm gear ,that most of you i think you don't want to buy) And the worm gear link:https://item.taobao.com/item.htm?spm=a1z09.2.0.0.NGtbdA&id=17352109451&_u=765kgh64ed9 I really don't whether you guys can open it and buy it..... and the rod that worm gear needs is 4mm&6mm (if you buy it maybe you need to buy too ) and you can get it too from the same place,and the links is:https://item.taobao.com/item.htm?spm=a1z09.2.0.0.NGtbdA&id=45114001387&_u=765kgh6babe