Sponge Stamps

I found from website can DIY foam stamps using bottles lid. So I was collecting bottle lids now.

However, I found this sponge stamps from Daiso at IMM which cost only S$2, which can save my time effort for DIY the foam stamps. But I am only able to get the upper case set, lower case set of sponge stamps are not available. Maybe I still need to DIY for is set.