The first option we think of and the one we usually consider the most resistant to join the wooden pieces of a piece of furniture are the box and tenon joints, but sometimes we may not have the means, time or skill necessary to perform this type of joint, so it is always good to have at hand a doweling jig (you can find some between my DIY woodworking jigs). I have the Wolfcraft doweling jig, the one that is formed by two metal pieces (one to hold both boards and the other that moves to drill the holes) and that comes in handy to join the edges of boards or boards reinforcing the joint with tubing, but I think that a self-centering tenoning guide, like the one used by Matthias in this article where he makes changes in a kitchen table, can be much more versatile.
If you are concerned that the strength of the tubulars will not be sufficient, I personally believe that the four 12 mm tubulars used for each joint will not be as strong as the box and spigot joint. Moreover, as he says in the article, there are tables for sale with very simple joints that are much, much weaker. And, as you might guess when you read this article, being a small guide it fits perfectly in your suitcase and you can take it with you to use it for any project that comes up wherever your friends or family live when you visit them. The only downside is that, apart from a few online hardware stores, I never found that particular model of doweling jig for sale.
Look for the link to the Spanish article on this kitchen table modification using a Woodgears tenoning guide in the woodworking projects tab of this blog and there go to Woodgears translations (number 29).
