well, lets pretend I didn't originally try and link the output of a block to a previous block to try and 'recursively' call/use a Loop Block . Honestly though, depending on what you're nesting here and how deep the nesting goes (ie loops inside loops inside loops....) you could run into a memory problem (either a hardcoded retool one or one from your browser/platform) . in this case using more than 1 loop block might be a better option as memory can be freed after each block lowering overall memory used over the runtime length