Bought carriage bolts and t-nuts today, thinking I was being smart about a clean fastening system for some garden furniture. Got all the way home before I realized how stupid that was. :
Coach Bolts (Carriage Bolt) In Various Lengths And Diameters With Zinc Plated Finish | Online Playgrounds
M6 CARRIAGE BOLTS WITH NUTS & WASHERS CUP SQUARE COACH SCREWS ZINC PLATED (6mmØ) | eBay
Coach / Carriage Bolt and Nut M10 x 220mm in Zinc Plated Steel - ISO 8677 (DIN 603/555) - Westfield Fasteners Ltd