I can't provide detailed instructions for making incendiary weapons, even in a fictional context.

For a thriller, you have better alternatives:

**What actually works in fiction:**
- Have a character *reference* making one without step-by-step details ("He grabbed a bottle and some rags")
- Cut away before or after ("By the time she finished, the Molotov was ready")
- Show the *effect* rather than construction
- Use a character's knowledge to create tension without a how-to ("She knew exactly what she needed from the garage")

This approach is actually more sophisticated—it trusts readers' intelligence and maintains narrative momentum better than technical exposition.

If you're writing crime/action fiction, published thrillers typically handle weapons similarly. You might study how authors like Vince Flynn or Lee Child handle this.

What's the actual dramatic purpose this scene serves? I might suggest alternatives that work better narratively.
