Initially I use hollow tubes to provides support for the pots to get it level and stable.
Finally I manage to find the right pot made by Gafri product code GP 170, this so far the only pots that I found which is big enough to and just narrow at bottom to be place in the gutters without problem. There are two colours available white and brown.
They are available from Plants nursery for around RM1.60 to RM2.00 depending on where you shop. I bought it from Greenish City GardenMart in Shopee.
Gafri is not a big manufacturer of pots like Babas so do search around for these if you not able to get the right size pots.
The Babas RD 170 won’t fit into the gutter growbed.