Ah, the good ol' DIY journey

I'll share my experience with ya.
I've been down this road many times as well, like
@simonhill55 mentioned, acrylic won't adhere to glass with silicone very well. I'm not entirely versed with the variables which affect curing, but I assure you if you happen to get a "descent" bond between acrylic, glass, and silicone, it will have a limited lifespan regarding strength. You might get 6 months, you might get 2 yrs, but it will always fail.
I've bought many pieces of tempered glass with beveled edges to make baffles, from Dixie Glass Hoppers in Decatur over the years. They're good people. This makes a rockstar DIY sump with a 40 gal breeder or 30 gallon extra high (they're made by Deep Blue Professional aquariums.). The guys at Premier Aquatic up in Marietta can order them for you. If you need to drill the tank, for using an external return pump, buy a Drilax diamond hole saw kit and a Drilax hole saw jig, off of Amazon. TRUST ME, you will want to use these tools to drill if you don't want to blow through a bunch of tanks and cuss for a few hours
https://www.amazon.com/gp/product/B00V3UONCW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
If you want to DIY your own sump from acrylic, I've found it much easier to work with cast rather than extruded. It is more expensive but worth it in my opinion. I started with a table saw and a 40 tooth blade. I upgraded to a fine 80 tooth blade but didn't see any improvement in the cut. The 80 tooth does better on soft plastics like polyethylene. You can also flame polish the edges to make them easier to bond, but it's really tricky with propane, you can burn the edges SUPER easily. You're better off with high grit sandpaper to polish the edges before you bond them with solvent. Flame polishing uses a much lower temperature and you'll have to buy hydrogen and oxygen cylinders from Airgas or others to run it.
I then upgraded to a CNC machine, the X-Carve made by Inventables and the V-Carve software by Vectric. This made BEAUTIFUL cuts, after some trial and error with the end mill, spindle speed and feed rate. It's still a pain in the rear to set the machine up and make all the cuts, you won't save any time, but if you enjoy spending a weekend on it, it will look nice.
Laser cutter is the ultimate, I just bought a BOSS laser but have not yet got it set up for cutting acrylic like I'd like, will take more experimentation.
The long and short of it is, if you're wanting to save money, honestly just save up and buy a pre-fabricated sump. It will last a long time and will look nice. Trigger Systems makes gorgeous equipment. If you enjoy the DIY experience with mixed results and have weekends to burn, go for it!