The etches for inside motion are included in the GWR kits, which allows construction of a non-working, ‘dummy’ inside motion. Additional kits are available to convert these to working inside motion. They include lost wax axle cranks, turned brass eccentrics, rivets and detailing parts and instructions in order to assemble fully working inside motion. For those who have an earlier kit without the etches, the full inside motion kit is still available.
| Ref | Locomotive | Price for full kit | Working parts only | |
| IM 1 | Aberdare 2-6-0 | £25 | £20 | Download instructions |
| IM 2 | 3232 2-4-0 | £25 | £20 | Download instructions |
| IM 3 | Bulldog 4-4-0 (straight frame) | £25 | £20 | Download instructions |
| IM 4 | 28xx 2-8-0 | n/a | £12 | Download instructions |
| IM 5 | 2251 0-6-0 | £25 | £20 | Download instructions |
| IM 6 | Stella 2-4-0 | £25 | £20 | Download instructions |
| IM 7 | 1854/2721 0-6-0PT | £25 | £20 | Download instructions |
| IM 9 | Hall 4-6-0 | £20 | £12 | Download instructions |
| IM 10 | Atbara/Bird 4-4-0 | £25 | £20 | Download instructions |
| IM 11 | 2301 Dean Goods | £25 | £20 | Download instructions |
| IM 16 | City 4-4-0 | £25 | £20 | Download instructions |
| IM 23 | Bulldog 4-4-0 (curved frame) | £25 | £20 | Download instructions |
| IM 25 | Duke 4-4-0 | £25 | £20 | Download instructions |