I came upon an ad for this easel for tablets and smart phones. It looks pretty good to me although I've seen it only in the pictures in the ad. According to the ad, it's made of metal; judging by the variety of colors available I expect it's probably anodized aluminum. It would need some velcro to be secure for use on a sound cart but I thought the integration of a battery supply was a useful feature, permitting use away from AC without taxing the battery used for the recording gear. At only a bit over $40, it might be worth a try.
David
https://www.opensky.com/vistashops/product/podium-style-stand-with-extended-battery-up-to-200-for-ipad-iphone-or-any-smart-gadgets?osky_origin=liveintent&osky_source=cpc&osky_campaign=vs-podiumstand&utm_campaign=vs-podiumstand&utm_source=liveintent&utm_medium=cpc