How One DIY Enthusiast Built 13 Custom Coffee Roasters

Ever wonder how much control you really have over your coffee’s flavor? Most store-bought roasters offer limited settings, but one former mold maker in Shanghai took matters into his own hands—literally—building not one, but 13 custom coffee roasters to roast beans exactly to his liking.

The answer? Thirteen. That’s how many roasters the shop owner, Li Jun, has built from scratch—including one modeled after a 17th-century German design and another using everyday items like a pressure cooker and a streetlamp base.

A Café with a Hidden DIY Gem

Nestled on Li Huangpi Road, a Shanghai street known for its historic charm, lies a café called “Mojie Coffee” where the décor alone transports visitors back in time. The space is filled with vintage telephones, radios, typewriters, and even an old accordion. But the real hidden gem isn’t the retro interior—it’s the custom-built coffee roasters tucked away in the shop.

While the café’s resident cat, Dou Dou, has drawn some attention, it’s the roasters that truly set the place apart. Many customers are surprised to learn that the beans they’re drinking were roasted on machines crafted by the owner himself.

The 17th-Century-Inspired Roaster

One of Li Jun’s most elaborate creations is a roaster modeled after a 17th-century German design. It took months of nonstop work to complete. The roaster features a stainless steel bowl with the bottom removed to serve as the bean loading chute. A thick pressure cooker was hollowed out to create the roasting chamber. Even the details were handmade: the drawer handle from a four-drawer cabinet became the roasting chamber door, a computer chair was stripped down to its lift column to serve as the base, and the entire machine stands on an authentic streetlamp base—just like the ones you see on city streets.

The Simplified Daily Driver

In contrast, the roaster that barista Juanzi uses daily is far more straightforward. It’s built into a glass cabinet and consists of an electric hot plate surrounded by sheet metal. Two kitchen-style mesh strainers, placed dome-to-dome, form the roasting chamber. Every aspect of the roast—heat level and duration—is manually controlled. There are no digital timers or pre-set profiles. Just pure, hands-on roasting.

Why Handmade Roasters?

Today, all three Mojie Coffee locations use Li Jun’s custom-built roasters. While some may wonder why he doesn’t just buy commercial machines, the reason is simple: flexibility. “Store-bought machines are rigid. They force you to follow their fixed programs,” Juanzi explains. “But coffee beans from different origins require different roast profiles, and every roaster has their own style. With our homemade machines, we have full control.”

Another key advantage is batch size. The DIY roasters are compact, allowing the team to roast only as much as they need. “We roast only what we’ll use within a week. Freshness is everything—it matters more than origin,” she adds.

Frequently Asked Questions

How many custom coffee roasters did the café owner build?

The café owner, Li Jun, built a total of 13 custom coffee roasters. These include a detailed model inspired by a 17th-century German design and other variations using everyday items like a pressure cooker and a streetlamp base.

What makes the 17th-century-inspired roaster unique?

This roaster is modeled after a 17th-century German design. It features a stainless steel bowl with the bottom removed for loading beans, a hollowed-out pressure cooker as the roasting chamber, a repurposed cabinet handle as the door, a stripped-down computer chair as the base, and an actual streetlamp base—identical to those found on urban roads.

How is the daily-use roaster different?

The daily-use roaster is housed in a glass cabinet and consists of an electric hot plate surrounded by sheet metal. Two mesh strainers are used as the roasting chamber, and all roast parameters such as heat and time are manually controlled without digital automation.

Why doesn’t the café use commercial roasters?

Commercial roasters are inflexible, forcing users to follow preset programs. Homemade roasters allow full control over roast profiles for different coffee origins and personal preferences. They also enable small-batch roasting, ensuring beans are used within a week for maximum freshness.

How does freshness impact the coffee?

Freshness is considered more important than origin. The café roasts only the amount of coffee needed for about a week’s use to ensure optimal flavor and aroma, which can degrade quickly after roasting.

Recommended FrontStreet Beans for DIY Roasting

For home roasters experimenting with custom setups, try FrontStreet’s Ethiopia Humbera for bright citrus and floral notes, Yirgacheffe for juicy berry and lemon zest, or Brazil Queen Manor for nutty chocolate balance. Each highlights how roast timing and temperature—key when using DIY equipment—affect flavor. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.