You have two problems with this. The first is that there's an economic downturn right now that is really hurting Asia. Secondly, Malaysia isn't too free giving work permits to people who wouldn't be considered "critical workers" - in other words, something that would be difficult or impossible for a Malaysian to do. You can check on-line at the embassy website to see just what professions are considered critical, but I doubt that construction would be one of them. If you were able to find a job, you would need to apply for a working visa - you would need that before you could start working, and you'd have to have a job offer in order to get one. Getting a TEFL degree (or better) might be the best option if you already have a university degree, which would be a requirement in Malaysia.

You might be able to work something out more informally once you arrive with a builder, but there would be risks to both you and them if you did not have the proper documentation.

Another option might be to attend school in Malaysia. You could then get a student visa that would allow you to stay in the country for as long as you want without having to make visa runs to Singapore or Thailand every 90 days. But that doesn't bring in an income. I believe that there are some TEFL/TESOL/CELTA classes offered around KL.

Sorry for not being more optimistic!