I don’t know what the email you sent them looks like, what day of the week you sent it, or how long it’s been since you sent it so for all I know you could have done all this already.
First off email:
1. Be courteous and professional throughout. Start with “Dear Mr/Mrs ______,” and end with “Sincerely, _________”
2. Introduce yourself (full name) and explain how you learned about their product.
3. Explain your interest in their product (you think it looks good and want to purchase) and your intended use. Be specific in your explanation here, you are building a drop in ramp for a summer jib set up. The ramp is X feet high, X, feet wide, at a pitch of X degrees, etc. Include details like the expected square footage of powderpack you are going to need. Details like this are good because they show you have put some thought into the project and aren’t just some whimsical jackoff wasting their time.
4. Indicate an interest in purchasing additional products from them in the future. For instance if the powderpack works well, maybe you know others who are interested in doing similar projects or have other projects in mind for yourself.
5. Express appreciation for them taking the time to read your email, and say something like you are looking forward to hearing back from them.
6. Provide contact information. Full name (again), phone and email.
Day of week and time:
Monday, Tuesday or Wednesday are your best bets for sending stuff. Thursday is ok but by Friday, in an office, most people are already mentally checked out. Mornings are best as well since people generally check there emails shortly after arriving to work. Afternoons and evening emails are much more likely to get buried under loads of other emails.
How long to wait:
Wait one week for a response and then follow up. Wait another week, if still no response you're not likely to get one.
I hope this helps.