I love to create abstract collages using all kinds of mixed media. In addition to random papers, magazines, newspapers, and old books, I like to use the following supplies.
Abstract painted papers are a great basic supply. These come in packets of either warm, cool, or mixed colors. (Affiliate link)
Collage Paper Pack, Modern Mixed Media Paper Sheets.
I use an acrylic matte medium to assemble my collages. Utrecht is a good quality, reasonably priced option. (Affiliate link)
Utrecht Artists Acrylic Fluid Mediums
I love to use these inexpensive pallet knives to apply the acrylic medium. (Affiliate link)
Richeson Plastic Painting Knive Set - Set of 5
I really like this heavy duty mixed media paper. Comes in a variety of sizes. 184 lb, 300 gsm (affiliate link)
Strathmore 400 Series Mixed Media Pads
I love these paint pens for adding color and texture. Affiliate link
Posca Paint Markers and Sets
I also like to add a bit of paint to my collage designs. These are good quality for the price. You can buy sets or individual colors. Affiliate link
Blick Matte Acrylic Paints and Sets
These are some of my original abstract collage designs made with supplies from this list. I sell them on Etsy along with some of my other artwork. Affiliate link
Small Original, Mixed Media Abstract Art
A good pair of scissors is a necessity. I love these. Affiliate link
Scotch MultiPurpose Scissors
When working on collages, I always use inexpensive brushes. These are reasonably priced and get the job done. Affiliate link
Blick Economy White Bristle Brushes and Sets
When your collage is finished, you can frame it nicely in these standard sized frames with mats included. Affiliate link
Blick Emery Gallery Frames with Mat
Stencils can add a bit of texture to your designs. I love to collect them. This is a great collection. Affiliate link
14 Pcs Layering Mixed Media Stencils Leopard Diamond ...
Here are some more of my abstract work that I sell on Etsy. Affiliate link
Small Painted Collage Art
These are reproduction prints of modern abstract collages.
Which Way #2 by Nancy Merkle
Some cruciform style abstract collages.
Nancy Merkle Cruciform Series Wall Art
You can also use a gelli plate to create your own colorful paper prints. Affiliate link