Has anyone come across concrete forms like this picture sold in Thailand? Mainly what I need is the pour above grade to be round & neat and have a smooth, level top. If not available, any substitute ideas? Some sort of forms are a must as it will be vibrated.

PVC or concrete pipe?

No need to take it off after the concrete has set, already has a nice smooth surface finish.

Yep, concrete pipe is the norm - cheap and available in several sizes. Only issue is they're typically only 2.0-3.0M long, so bell ends will be visible if you need to stack them.

Yeah, I could use those cheap concrete pipe segments as the forms need to be just a half meter each. The downside is I need 25 of them which is a whole bunch and it is a bit tricky cutting those pipes with an angle grinder to have a nice squared up and smooth enough top for screeding. I also want to add some concrete color so would break the pipe form off above grade after it sets. Anything necessary/good to prevent sticking in this case?

Yeah, I could use those cheap concrete pipe segments as the forms need to be just a half meter each. The downside is I need 25 of them which is a whole bunch and it is a bit tricky cutting those pipes with an angle grinder to have a nice squared up and smooth enough top for screeding. I also want to add some concrete color so would break the pipe form off above grade after it sets. Anything necessary/good to prevent sticking in this case?

These pipes are normally made 'cottage industry' style - see if you can find someone who actually makes them (rather than just reselling) and have them made to order.

Look for a place with both finished pipe sections and steel molds sitting around

homemart in cha am have them so I guess every outlet does, or can order.

the cardboard forms I mean.

The Homemart near me also stocks a few standard sizes, not sure what the prices are.

I just bought some 150mmx2500mm cardboard tubes from "Singchai Industry" 02-451-4479 for 230B each.