Robern's M series medicine cabinets are modular and can be ganged together. They have matching inline lighting for a seamless surface.

https://www.robern.com/products/medicine-cabinets/m-series-cabinets/flat-top/mc2440d4fble4/

https://www.robern.com/products/lighting/inline-lighting/vertical/ml3530ilsfmrdv/

https://www.robern.com/inspiration/inspiration-gallery/#/inspiration/1726/

https://www.robern.com/inspiration/inspiration-gallery/#/inspiration/1956/

https://www.robern.com/inspiration/inspiration-gallery/#/inspiration/1960/?ROOM_TYPE=Master+Bath

I'm doing a 40" expanse (two 20" wide medicine cabinets ganged together) using the Robern PL series which is a bit more affordable than the M series. I'm then doing above medicine cabinet lighting with a regular overhead vanity light fixture which is not as ideal as side sconces, but it's a hall bath so I'm not too picky.

You didn't mention if you had a double or single sink. Since you are doing a 40" expanse, if you only have one sink, this 40" Kohler medicine cabinet would work. Kohler is made by Robern or vice versa.

https://www.us.kohler.com/us/verdera-lighted-medicine-cabinet-40-x-30/productDetail/medicine-cabinets/1482496.htm?skuId=1481768&brandId=1313532

or non LED version https://www.us.kohler.com/us/verdera-40-x-30-aluminum-medicine-cabinet-w-adjustable-magnifying-mirror-and-slow-close-door/productDetail/medicine-cabinets/942121.htm?skuId=942107&brandId=942122

Sink is off-center (right side). Not the original poster though.

I'm the original poster. I will have double sinks and a 60" wide vanity. Trying to figure out the most economical way to do this. I saw 3 of the LED lighted kohlers that patty111 mentioned today, they were in a row, ganged together and that was pretty nice, especially if they can be recessed. I would like some outlets for electric toothbrush and electric razor. Not sure how great the lighting is? (Store had lots of windows, so could not tell.) Anyone know and like them? I have been looking at the roburn site, but I am having a hard time imagining what they would look like together, but I will look again.

Custom build or trim?

This is my old home remodel with a craiglist find

Not sure I understand the question? The vanity is a custom built vanity (but with limited options.) I don't want any trim or wood around the mirrors if possible (though yours looks lovely.) I am going for a modern, minimalist look.

These Fresca medicine cabinets can be recessed or surface-mounted:

• Fresca FMC8019 59" Wide x 26" Tall Bathroom Medicine Cabinet with Mirrors
• Fresca FMC8020 59" Wide x 36" Tall Bathroom Medicine Cabinet with Mirrors

http://sofiamedicinecabinets.com/products/index.php?main_page=index&cPath=187_200_224_243

Here is how we did ours. We made the cabinets and recessed them then mirrored

the remainder of the wall. I’ve included a pic of the bottom of the cabinets.

the bottom

@cyndi62 I wound up getting 2 robern (M Series I think?) medicine cabinets and 3 robern mirrored lights that go vertically on either side of the cabinets and in between the two, so it winds up being a whole expanse of mirror. They have great storage space and we are enjoying them very much.

Pictures of the finished product?

For size, you can also get customized sizing where cabinets can be ganged together. For example, two 12 inch cabinets ganged together or two 15" ganged together would work where you can add lighting as an option and have interchangeable left or right open doors. It gives you alot of storage over your vanity without looking too wide. And if you want to spend the extra cost, you can have them recessed mounted as well. This will make them look flush with wall and less bulky over any sized vanity. And some of these mirrored medicine cabinets have integrated LED lighting, which can also offer a nightlight with dinner function. So, you will not only have lighting from your main bathroom, but an additional light source. I hope this helps