I'd love to grow some things on my window sill, which is about 6 inches wide. I can't fit tons of conventional planters on that area, so I'd like to build my own.

I'm planning on growing cucamelon, most guides online say that I should plant in a 5 gallon planter, so I'm assuming I can make a 6" x 6" x 36" and have that be enough (for 1 or 2 plants). Let me know if my math is off

The hard part is deciding what to make it out of

Cement:

• Pros: Easy to waterproof, can essentially pour it into mold, cheapest option
• Cons: Messy, requires a lot of time, have to build a mold (I'm using cardboard and tape), heavy

Hypertufa:

• Pros: Easy to mix, lighter materials, easy to construct
• Cons: Messy, requires time to cure, have to build a mold, harder to waterproof

Acrylic:

• No mold required, short cure time, can see roots growing through clear acrylic, waterproof
• Cons: Expensive, hard to construct (never cut glass or plexi before)

Technically I've never mixed cement or hypertufa either, but it looks a lot easier to do (more forgiving to fucking up). I'm assuming I can follow some directions for making an aquarium and have it hold up relatively the same? If not, let me know.

I'm heavily leaning towards Acrylic, especially if my math is somewhat accurate, but please give me some tips/advice on how to move forward. If Acrylic is the hardest to pull off well, I'll abandon it.

Waterproofing is fairly easy with rubber spray and light won't be an issue with a coat of paint, but every choice has some degree of difficulty.