I've made some similar:
If I was quoting a custom made one I'd quote ~4 weeks. A week to get it setup and poured, a few days to apply finish, more time add the electronics, any shipping times, etc. This is all after work hours for me, not sure if you are doing this stuff as a side gig/hobby like me. Maybe 2 weeks if you weren't working also.
I drilled a hole through the bottom and wired mine up myself. Some screw wire caps, lamp cord, outlet plug, switch, light socket, and LED bulb. I used these bulbs below, but it's not a string style.
https://www.amazon.com/gp/product/B07D3S9RXZ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B07T4NPS1H/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Since you've done other projects and even tables you likely have all the tools you need/know how to finish it.
The hardest part for me was figuring out the wiring, so do some research on that first. I went with wall plugs cus I didn't want to deal with a battery pack. If you do a battery pack just make sure it has the right voltage output for the lights and connect them to a switch and you're pretty much good to go.
Let me know if you have any specific questions now or when you get started and I might be able to help.
edit: for reference I've sold mine ~$80-120 depending on the size. The one pictured was on the higher end because it was like 14" tall.