Woodworking

So I've long dreamed of designing & making my own computer desk, and I love the things I've seen people do with epoxy resin. After poking around online for a few months, I found a few posts that gave me sufficient inspiration (see below) to come up with a design concept.

• https://www.reddit.com/r/woodworking/comments/bwouom/my_first_attempt_at_a_epoxy_resin_desk_thank_you/
• https://www.reddit.com/r/woodworking/comments/pu1few/wood_led_desk_i_made_from_scrap_cuts_probably_my/----

I had two questions for the community here, hoping to get some advice:

1. For that innermost rectangle (the one with all the triangles), ideally they'll be spaced out evenly across the entire available area; what I can't figure out is how I'll ensure they keep their positions while I'm pouring resin in between those cracks. Maybe a light application of caulk to "glue" each triangle in place to the bottom of the mold when I'm pouring? Or should a run a small piece of wood behind each row or column of triangles to mount them onto? I feel like that might detract from the aesthetic look I'm going for, but probably not as much as "screwed up triangle placement" would...
2. Also for that innermost rectangle, I hadn't intended to fill it entirely with resin, in order to save cost/weight. The space is 2.5" deep, but the triangles will be only 0.75" deep. Can I get away with maybe doing a 1.5" epoxy pour in there, or is it likely this would compromise the structural integrity too much?

Any other advice for doing epoxy resin pours would be appreciated, I'm excited to begin working on this and simultaneously terrified I'll screw it up and waste all the materials I've been compiling.