Blogs dedicated to the custom design of metal cans is very niche . However, there are several blogs and websites related to packaging design, branding, and industrial design that might feature articles on custom metal can designs as part of their broader content:

1. **The Dieline** - Focuses on package design and branding, which sometimes includes custom metal can designs.

   URL: https://thedieline.com/

2. **Packaging of the World** - Showcases creative packaging designs from all over the world and might feature custom metal can designs.

   URL: https://www.packagingoftheworld.com/

3. **CanTech International** - This is a magazine dedicated to metal packaging and includes coverage of custom metal can design within the industry.

   URL: https://www.cantechonline.com/

4. **Packaging Digest** - While it's more industry-focused, this publication sometimes features innovative custom metal can designs.

   URL: https://www.packagingdigest.com/

5. **Lovely Package** - Features a wide range of packaging designs, including those for metal cans.

   URL: http://lovelypackage.com/

6. **World Brand Design Society** - Showcases brand and packaging design work, where custom metal can designs may be featured.

   URL: https://worldbranddesign.com/

7. **Packaging Innovations** - Covers innovations in packaging, including sustainable and custom design, which could intersect with metal can design.

   URL: https://www.packaginginnovations-online.com/

8.**Blog about Metal Packaging** - Exclusively dedicate to the custom design of metal tin cans, including sustainable and custom design, shared by a canmaking manufacturer China.

   URL: https://www.boxestin.com/blogs-about-metal-packaging/

9. **Ambalaj** - This is a design blog focused on packaging and might occasionally feature posts on custom metal can designs.

   URL: http://www.ambalaj.se/

10. **Brand Packaging** - Discusses packaging design's role in branding and often showcases custom packaging solutions, potentially including metal cans.

   URL: https://www.brandpackaging.com/

11. **Packaging World** - Offers insights and examples of packaging, sometimes including custom metal can design.

    URL: https://www.packworld.com/

NOTE: The coverage of "custom design" for metal cans might be found within broader topics like "packaging design," "branding," or "innovation in packaging." The URLs and blog focus can change over time, so you may need to search for the most current and relevant content on these sites.