For most of the crosstabs it's actually fairly close to the general results. There's a 15-20% of people of all demographic alignments that like the idea. 19% of women support the Atlantic Wall (65% opposed vs. 17% of men, 72% opposed) and 19% of hispanics and 10% of blacks. (20% of whites.)
31% of Trump supporters support the idea but that may include wall enthusiasts who are drawn to Trump because he's the only clear pro-walls politician since East Germany collapsed.
29% of people 18-29 support such a wall, only 53% opposed. Their net favorability of the idea is actually the same as Trump supporters. Even though they're 52-22-6-8 for Hillary-Trump-Johnson-Stein and 63-24 for Hillary-Trump.