TLDR: expect to wait, but the product are well made.
To start, it's not obviously shown right away, but all products are made to order, apparently.
Another note, the other place I ordered from was very fast for me, but I called first to let them know I was on a time crunch. Also, another hobbyist ordered from them without calling or anything, and the time frame was similar to Tenecor.
If you want good acrylic accessories, expect to wait. Regardless of the vendor.
I ordered 2 overflow boxes, but after a week of no updates, I ordered basically the same thing from another place. Finally after about 2 weeks, I emailed about the order, I only got an automated "shipped" email the next day. 1 of the 2 from Tenecor showed up. Packed well. Nicely built, but I was on a time crunch and had already received and installed the 2 other ones.
I emailed Tenecor saying I only received 1 of 2 (the first box was big enough to fit at least 2.) But only got an automated "package has shipped" a day or 2 later. So, quality is good, but don't expect "rush processing and delivery" or personal correspondence.
---I was being "that guy," I'll admit, so I wouldn't say I had a particularly bad experience---