DIY Filter Cartridges for s10 slim filter

[GodFan]

I bought a Marina 5 gallon tank kit for guppy fry a few months ok and it didnt work out. The tank then moved to the garage. Well now my brother wants frogs and so Im giving him the tank.
One problem however was the filter cartridges. I despise the slim filter cartridges. They are expensive and I really dont trust them. When I got the kit it had 2 cartridges, one labelled tropical fish and one labelled goldfish. I think it is confusing and again I dont trust it. So I decided to make my own.
Right now I am planning on using an old wire hanger as the frame. I am gonna buy the filter media in a sheet I can cut myself. I guess I will just staple it over the hanger? (Ideas?) I am gonna fill one with activated carbon and one with a pack of rocks to promote bacterial growth.
Does anyone have any ideas about how to connect the media? I thought sewing or staples. Also should I buy a pack of rocks designed for bactderial groeth or use a smashed ceramic pot?
Thanks and God bless!

[MrBeta]

I'd stay away from any metal due to rusting but there's no reason you couldn't DIY your own.
I'd use ceramic rings and maybe a filter pad/floss

[GodFan]

Ok thanks. Where do you get the ceramic rings?

[MrBeta]

LFS, Ebay, Amazon. They're everywhere. I don't know normal prices but I think I saw a pound of them for 10 bucks shipped on ebay.

[GodFan]

ok thanks! I appreciate it