Redditの「r/3Dprinting」に、EtsyでTPU製スマホケースを販売して月商1,800ドル（約27万円）を達成したというレポートが投稿されて、大きな注目を集めているんです。

スマホケースを選んだ理由はシンプルで、需要が安定していることとデザインで差別化できることの2点。投稿者はキャラクターテイストのオリジナルデザインに特化して、量産品との正面衝突を避けているとのこと。

Guess what's buzzing on r/3Dprinting? A seller is reportedly raking in $1,800 a month (that's about 270,000 yen!) selling 3D printed phone cases on Etsy. Seriously, is this for real?

These custom phone cases are apparently selling for $25 to $40 each. And get this – the material cost per case is a mere $0.80 (around 120 yen). The profit margin on that is insane! I was honestly floored by how lucrative this could be. We're all surprised, right?

素材と原価の話

使用素材はTPU（熱可塑性ポリウレタン）がメイン。フレキシブルで衝撃吸収性があって、スマホケースとしての実用性が高いんです。原価は1個あたり約0.8ドル（フィラメント代のみ）で、販売価格は25〜40ドル。後処理の手間を含めても利益率は高めとのこと。

Etsyでの差別化は「速さ」と「オーダー対応」

人気のデザインは在庫を持ちながら、「スマホ機種指定でカスタムしてほしい」という需要にも対応しているとのこと。Etsyでは「ハンドメイド感」「対応の丁寧さ」が評価につながるので、メッセージへの返信速度を重視しているそうです。

日本のminneやCreemaでも同様のビジネスモデルは成立しそうですが、スマホの機種が多くて対応パターンをどこまで増やすかが鍵になりそうなんですよ。

The Setup: Surprisingly Standard

The 3D printer being used? An Ender 3 V3 SE. That's a model that typically costs under 50,000 yen, pretty much like the one in my office! We're not talking about some high-spec industrial machine here. The fact that you can achieve this much with an accessible entry-level printer really sparks some hope.

For materials, they're using PETG. My guess is PETG was chosen over PLA for its durability and flexibility – phone cases get dropped a lot, so you want something less prone to cracking, right?

Design: It's All About Customization

Design-wise, Fusion 360 is the tool of choice. It's CAD software, which does have a learning curve, but there are tons of YouTube tutorials out there, so self-learning is totally doable. The key here isn't just selling a product, but offering unique, personalized designs. That's why people are willing to pay a premium. Everyone loves something that's 'just for them!' (lol)

This seller claims to have hit $1,800 in monthly sales by February 2026. If you can earn that much on the side, your life gets a whole lot easier. Honestly, this isn't just a side hustle anymore; it's practically a full-time income!