Hi Oleladyintheshoe and welcome, I have worked with concrete, but not to make a birdbath or pond liner. You're post got my curiosity up so I did a quick Google search and found some instructions. Here is a link

Here is a link that might be useful: formless concrete bird bath instructions

Hmm, thanks for the response. This seems pretty compex, in the "alot of work for a small area" type of way, but still doable for a birdbath. I had read on here about digging a hole for the molds so I think you could still use this with those instructions. Still not understanding how to use it for a pond liner. The original post said to use like waterbed or old pool liner then re-inforce with cement. Course, now that I think about it, I have only used quick-crete. Is that the same as concrete? Sorry, I didn't mean to say that out loud:) I am completely new to all this and still feel that I can do ANYTHING....if I only knew how!

Right on olel. quick-crete/concrete are basically the same. I'm not sure about the digging a hole method for your molds, but sounds like it makes sense - maybe someone else can point you to the original post. best of luck, eatsivy

Thanks thanks thanks. All I know is that as of yesterday it was on page 13 (did I mention I've been obsessed)under "making birdbaths". Idk how to link posts .....YET!

I'm late to this thread but bird baths made from concrete are pretty easy. I'll post a link below. I haven't made one but I've made many rhubarb leaf stepping stones which are pretty much the same thing except they are flat.

I have no experience with using concrete to line a pond but I think it might be easier to use either a rigid fiberglass or plastic liner or a flexible plastic one. I've found two of the rigid plastic ones at yard sales for $25 and $40. If you do decide to use concrete I think you can make the concrete mix fairly stiff and trowel it on to a wire form made of chicken wire perhaps. Must be info on the net on how to do this.

Here is a link that might be useful: sand cast bird bath

I sent that link to my crafty and artistic 15yo.