How to I build an overflow in a tank?

[IluvHockey]

Okay I have read a bit of info before starting my tank. It looks like I will be buying used equipment with a sump. From what I have been reading it looks like a hang on cpr overflow is not a reliable as a built in one. And I am totally scared of having a flood if the siphon breaks. So the questions is do I just buy some arcylic to build my own overhang and silicone it in the used display tank I bought??? Then get someone to drill the holes in the used display tank to connect it to the sump. Can some one provide me a DIY link to help me out.

Thanks