I made this threaded insert tool to hopefully reduce the amount of material and cost compared to the ones I have seen available online. I used PLA carbon with a total material of 215.99 g.

 8 M3x4x5mm threaded inserts + 12 M3 Cap head screws are used.

The 100MM linear guide real I found on AliExpress for just over $4, MGN9C

Heat Set Insert Soldering Iron with Tips M2 M3 M4 M5 M6 Brass Hot Melt Inset Nut Embedded Thread Insertion Kit. Was also purchased from AliExpress, cost a little over $2.00.