I'd like to build a portable ramp that I can put up to my front door and inside steps whenever I bring my father over for a visit. Any suggestions on how to build a ramp that is fairly lightweight and secure? Both outside and inside have only two steps to get over.

there are pre-fabricated roll-away ramps that are great.

You didn't say how high these steps are or wide, its unclear if you have only one actual step between 2 different elevations or two steps - between 2 elevations (actually three steps).

Suggestions on making it yourself and if this is to be navigated via a walker or wheel chair - or motorized wheel chair, if person needs to be able to independantly navigate, or if you want an assisted situation where you'd be taking them back down backwards and braking a non ADA complaint ramp, etc.

If you come back and post info, I'll offer suggestions.