You can create $n nested loops with Algorithm::Loop.

If you want even less, work the module Set::CrossProduct does exactly what you want, wrapped in a neat iterator.

Another option is to the built-in function glob:

$ perl -wle 'print for glob "{1,2}{3,4,5}{6,7}"'
136
137
146
147
156
157
236
237
246
247
256
257
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