Start of by using a site like udemy (https://www.udemy.com), they are a platform for creating online courses and handle payments for you. They may have some users who are in your sector.

It sounds like finding 'customers' is your main issue. There is no panacea here, the approach you've taken so far is largely correct, here are some more ideas:

1. How about going direct to large construction companies (an industry you know) and offering them discounts for training their staff?

2. Reaching out to your own contacts to try and find more

3. Start a mailing list giving tips to these people and up-sell

4. The things you are already doing are good, blogging, social media etc. I would add creating meetup groups for engineers (and other target market).

5. Starting local is good idea, at least once you validate a customer acquisition model in the local area, you have something you can role out more widely.

If you want start an online course you must first know what others want. This is not what you want to teach others, but what they specifically want. You do this by building an email then asking. This is called a product launch. The first steps are to do a pre-launch. Once you have a large enough email list, start asking what they want. Then start giving it to them through 3 video presentations. Each video answers a different question and ends with the unanswered question for the next video. This sets you up as an expert. So, by the time you actually launch your product you will have a crowd waiting for it. That is if you have an email list. This crowd will grow over time, but you program your auto-responder email (e.g. Aweber) to go through the same series each time.

Best of Luck,
Mike
From the Trenches to the Towers Marketing
I will be willing to help as my time permits.
TheLittleGuysWayToRiches

1) Setup your course some where. Here are several ways that come to mind.
- WordPress + Paid Memberships Pro + WP Courseware
- Teachable
- Udemy or many other similar sites

2) Buy traffic from Outbrain or Taboola or Gemini targeting your landing page.

3) Buy small amounts of traffic + tune your landing page content to both match your traffic source terms of service + produce enough conversions to pay for your traffic.