When I first started experimenting with a standing desk, to see if it would work for me personally, I used odds and ends of household furniture two create two setups for test-driving standing desks.
But the Spark by Ergodriven is a much better option. It’s a flat-packed sturdy cardboard temporary lift, meant to be placed on an extant table or desk and thereby convert the furniture you already have to a standing desk. The Spark comes in threes sizes, allowing you to choose a desk suited to your height. It’s made out of surprisingly sturdy corrugated cardboard, and it’s pretty easy to assemble.
It’s also dirt cheap. Small Sparks for people under 5′ 4” or Medium Sparks for people 5′ 4” to 5′ 11 are $20.00 from Amazon; Large for people over 5′ 11” are $25.00. And because it’s flat-packed, it strikes me as something to consider if you do a lot of consulting that involves working from hotel rooms. You could have Amazon ship the Ergo Spark to your hotel, or stash it in your luggage and assemble it there. Most hotel rooms have a desk or table, and you can use the Ergo Spark to allow you to adjust your position from cramped and hunched, to standing.