How can I upcycle lampshades?

Paint them. Draw pictures on then & paint the design on. I painted a small one 3 yrs ago. I wanted purple & couldn't find one so i painted the color i wanted. Have fun.

https://www.pinterest.com/tickledpinktony/lampshades-upcycle-reuse-recycle-repurpose-diy/

I wallpapered mine.

Afton: here are some good ideas

https://www.diyncrafts.com/26537/repurpose/20-fantastic-lamp-repurposing-ideas-add-style-home-garden

If they are fabric shades you can dye them either solid or dip dye for an ombre affect.... https://www.ritdye.com/instructions/how-to-dye-a-lampshade/

ombre... https://www.ritdye.com/2018/05/02/dip-dyed-lamp-shade/

They have 2 formulas, one for natural fabrics and one for synthetic fabrics.

I used an old lamp shade to line a metal basket to update the boob light in my hallway. https://www.girljustdiy.com/boob-light-makeover/

I'm going to try to wrap jute around it and glue it on. Hope the end product looks as well as it does in my head.

You can re-cover your lampshade. The shape of it affects how difficult this is. For a simple cyclindrical one it is quite easy to glue fabric to the existing lampshade.

I did watercolor

How can I use a lampshade that’s missing the base, and there are no bases it fits.

You can paint or add wall paper and beads. I did some beading and turned them upside down and made a pendant lamp.

I used old slides

I used wide fairly stiff ribbon and wove it in and out of the wires. It was an antique lamp and I had purchased the shade at a garage sale. It already had the fabric removed. I loved it and it matched my bedroom beautifully with the antique furniture.

There are literally thousands of choices in ribbon. I just wrapped it around the corner and glued it and then wove until done and wrapped it around the last corner one and bingo it was done.